Petmailer is reeling from the vicious attack of the cultist, he is on death's door.  He assumes a defensive posture, aiming to dodge any attack at him next round and avoid any further attacks, trying to angle himself to make a run for the gate.  As a bonus action he takes a deep breath and focuses on all his training, gaining a second wind for the battle.

"Yeah, you better run, you piece of-" Harmony is interrupted by the cultist's blade slashing through her side. She glances down at the wound for a moment, then back up at the man with a sharp-toothed smile. "Nice try." With that, she disengages and makes a break for the door.

((You said that the family would make it to safety on the second turn. This assumes she's seen that happen or about to happen. If not, she'll dodge and stay put.))

Still in melee, Gunra will strike again at the nearest cultist.  These foes were competent and needed to be put down fast.

Attack: 9 Damage: 10

If able to safely do so, he will then use his movement to follow the others.

Seeing Harmony being attacked by the cultist, Nurm musters all his mental strength to help her.As his mind is almsot starting to touch the cultist's mind, he is interrupted by the other cultist charging him. In the last moment, he switches the focus to the cultist attacking him and connects with his mind instead.

Mind Sliver: 13 Int save, Damage 4, next save penalty 3

Nurm, you try to connect with the cultist's mind, and images of dragons and bloodshed quickly flashes through that momentary connection with the fanatic cultist's mind. The connection breaks, and the cultist makes a maniacal grin before attacking you again.

Against Nurm:

Gunra, you strike with you axe against the two cultists attacking you, but you miss. As you try to make your way to the gate, one of the cultists try to attack from behind.

Against Gunra:

Petmailer, you dodge the cultist as he tries to finish you up, and from where you are you will be able to reach the gate if you run to it. You hear familiar voices coming from the Keep, urging you to get in quickly.

Harmony, you disengage from the cultist trying to kill you and make your way to the Keep's gate. All attempts from the cultist and his lackeys to strike you are literally shot down when the archers start to aim at them once again, no longer in danger of hitting Harmony by accident. When you enter the Keep, you are greeted by a crying Roladd. "You are okay!"

To Kane/At the Keep:

When you enter the Keep alongside the scared family, Governor Nighthill is there. The right side of his face and head are bandaged, his right arm hangs in a sling, and his light blue tunic is stained with his own blood. It's obvious that he must have received these wounds during the early stages of the attack and hasn’t spared the time for more than cursory first aid.

"I'm glad to see that you made it here..." He says. He's eyeing your group and the ones still fighting outside, and his expression turns grim.

Petmailer says to Nighthill "Thank goodness you are here.  Is Escobert here as well?  We need to access the tunnel that he spoke of to escape.  I would like to take down a few of these cultists around the battlements to give us a little cover, then we can escape.  As a few of us remain to distract them, everyone else should escape down the tunnel.  After we have taken out a few, we will make a run for it.  Does anyone have some healing potions or a shield?  This will get dicey at the end, but it may just work to get us away from here."  

"Whoever wishes to stay and fight for cover as the children and families escape, come with me to the battlements, we will rain arrows down on them, we will give them a good fight today!"  Petmailer tries to show resolve and courage despite his injuries.  

Harmony pulls Roladd into a brief hug, taking a moment to scan him and the rest of the family for injuries. "Don't worry, I've fought much scarier things than these idiots with swords."

Suddenly struck with an idea, she makes sure she's out of view of the gate, then sends a message to the cultist who was attacking her. She mixes together some of the Draconic phrases she learned earlier and low, raspy Common. "Minion. You have destroyed enough. Return to camp. Obey me or perish."

Deception: 17

Seeing the rest of party safely retreating to the keep. Nurm also decides to let the archers deal with the cultists and begins to retreat to the safety of the keep, deflecting any incoming attack with his telepathic powers.

((Disengage and going to the keep))

Harmony, the cultist is doubtful and looks around, not sure where the voice came from or if it was what it seemed to be. Still, he drops his weapon and runs, repeating the message you gave him to any fellow cultist who tries to stop him.

Nurm, you arrive just in time to be part of the conversation.

Gunra, you are now the only one still outside until you post otherwise.

Nighthill nods, thoughtful. "Will that be necessary?" He asks. "Here inside the Keep they can't see what we are doing, and if they break in after we are gone, they might not find the tunnel..."

Escobert appears and interrupts the Governor. "Ya, about that. Since you are here, maybe you can talk him out of doing something stupid." He says, giving a not-to-pleased glance to him. "Before you arrived, we captured two cultists. They came to us and surrendered, claim to want to help, that's the only reason we haven't killed them yet." By the tone of his voice, it's obvious the dwarf does not believes that story for a second. "The people are terrified of them, and I don't blame them, but the Governor wants to take them with us!"

"Which sadly leads me to another question..." Nighthill says as he offers you a Potion of Healing. "That's the last one I have left, sadly. Tell me, did you happened to see any trace of Eadyan when you and the others were coming here?"

You are in the Keep's first floor. The archers are upstairs, at the parapet. Coming from there, there's also shouts and wails from what sounds like an angered mob in the making. Like Escobert says, it seems people really are terrified.

Kane realizes something when Nighthill says Eadyan. “Oh no...we forgot Leyding! What if she hurt? Or worse.” Kane seems genuinely worried. 

Seeing that it had some effect, Harmony repeats the message a few times to the various cultists she can see through the gate.

"I'll go check on what's happening upstairs," she offers, growing slightly concerned by the noise. She heads to the upper level to see what's happening.

Petmailer takes the potion of healing and says “Thank you, hold that thought, we need to see to this immediately.”  He pulls out his long bow and runs up the stairs after Harmony, to assess the situation from higher ground.  He will use the battlements for cover as he moves.  We need to assess the status of Greenest.

Seeing his allies safely make it in, Gunra will Disengage and move to follow the others into the keep as best he can 

Kane will stay with the family and Nighthill to keep them calm. He is still worried about Leyding. 

"...Leyding?" Nighthill asks turning to Kane, suddenly looking very shocked. "Wait, I remember now, you mentioned that name last time we talked. You said that it was Milo's experiment, didn't you? What was the experiment?"

Escobert runs to the gate to help Gunra in, and Nighthill's attention turns to them. "Shut the gate!" He orders, and as soon as Gunra and Escobert are inside the gate is closed and barred. You hear the group of cultists banging at the gate before being forced to run by the arrows raining on them.

Seeing as Harmony and Petmailer are already walking upstairs, Nighthill nods to Kane and turns to Nurm and Gunra. "Follow me" He says, as he walks upstairs towards the parapet. "This might complicate things, I'm afraid..."

When you reach the Keep's roof floor, you see what seems like dozens of townfolk reunited there at the center, while the archers are at the borders. Some of these townsfolk are badly hurt and receiving first aid, others are weeping, and a growing group are surrounding a chained figure and a fairly big cage, like the one you would use to keep a captured live bear trapped. Some of the guards are holding the chains of the figure and one connecting to what's inside of the cage, and others are busy with keeping the townfolk away from them.

As for the archers, they don't immediately notice you, busy as they are, but one of them does turn to look at you and the Governor when you all enter. You recognize her. "Finally!" Mentha says, honestly relieved. "Come here, I could use some help right now..."

From the parapet, you can see a good view of Greenest. All haystacks and barns are in flames, and a half-moon of burning buildings surrounds the Keep. That being said, while the cultists try to set all buildings ablaze as they move through town, thatch isn’t as flammable as it looks, and some of the homes and shops are still standing. Among them, you see the Temple: The rose garden has been burned and the stained glass windows have been shattered and destroyed, but the building itself is still standing.

The group of cultists that had been trying to get inside the Keep retreat and start marching towards the Temple. A cry of victory is uttered by the archers as they watch them go.

"...Will any of you idiots listen to me?!" 

The scream came from the chained figure. As you recognize the voice, you turn to look at him: The chained figure is Ignar, the one-eyed half orc cultist prisioner you had left at the Temple last night. He's badly beaten, and his arms have been chained behind his back. Seeing Petmailer and the others among the populace, he smiles bitterly. "Well, well, look who finally decided to show up!"

Arching an eyebrow, Mentha turns to look at you. "Do you know him?" The halfling asks.

At one side from where Ignar is, beastly growls and shierks can be heard coming from inside the cage. When you turn to look at it, you see that the caged "beast" is actually Leyding, but her fur and what's left of her robes are matted with dried blood. She has an iron muzzle on her that connects to the chain the guard keeping a watch on her is holding.

She's is cowering at one of the cage's corners, growling at the guard and the others like a scared animal, but the moment she sees you she immediately recognizes you and tries to reach you, jumping at the bars of the gate, tail wagging, but the fearful guard push her to the ground with one strong pull of the chain, misinterpreting the act as the gnoll trying to attack you. She falls back with a yelp, and growls at the guard.

"Stay back you demon, stay back..." The guard says. Silenced by the heavy muzzle, the caged gnoll just whimpers and growls.

From the survivors gathered behind you, you can hear fragments of their conversations:

"The dragon is gone, but it will come back any second now..." "Is that thing a cultist...? "Of course it is, just like the bugbear and the kobolds!" "The kobolds killed all of my livestock... They are all dead. What will I do now?" "My sister! Has anyone seen my sister?" "The orc has only one eye, like that one evil orc god... What is the Governor thinking?" "It bit me... That aberration bit me!" "The cultists came, and killed them all..." "Mom, I'm scared..." "Our priest is not here! The cultists killed him!" "Chauntea has left us" "We need to leave before the dragon kill us all"

The growing group of townsfolk who are surrounding the area where the prisioners are being held start to scream at the Governor, the guards pushing them back to keep them at a prudent distance from him and the party. Fear and anguish turning into rage, they point fingers at Leyding and Ignar, the captured cultist and his supposed gnoll helper. "Kill the cultists!" "Kill them before they kill us!" "Kill that demonic beast!" "Yes, kill the demon!" "Let us kill that thing" "If you won't kill the orc, at least kill that wretched servant of Yeenoghu" "Kill the cultists or we will!"

Nighthill tries his best to placate them, and glances at the party for some help in how to keep the heated situation from getting worse.

Kane hears the yelp from upstairs and goes to see the commotion upstairs. He sees Leyding and becomes angry. “WHAT ARE YOU DOING!!??” He runs over to comfort Leyding and tries to free her. “She’s not a monster!! Let her out!!” He turns to Leyding. “I’m so sorry that they treated you like this. Don’t worry, I’m here now...they won’t hurt you any more.” He turns to the guard. “Let her out now...or you will have something much worse to be afraid of..”

Harmony weaves her way through the crowd to stand next to Kane. "I don't want anything... unfortunate to happen here. I think it's in your best interest to open the cage and let us handle this." Her voice is deceptively calm, but her eyes don't leave the guard's, and she makes sure he can see her hand on the hilt of her rapier.

Intimidation (with advantage because Kane is helping? If not use the first roll): 11 8

The guard stares shocked at Kane, hand still holding the chain while his other hand slowly reaches for his mace, but gets stopped by Harmony's intervention. Terrified, he glances at the Governor for orders, whom just nods him to do as the tieflings say. He takes a step back, drops the chain and runs. 

The cage is locked by a latch and easy to open, but when you move to do it there's instantaneous panic on the crowd around you. "Kill it!" and variations of it are still being shouted but with more urgency.

Making his way towards you amongst the panicked crowd, Escobert orders the crowd to be quiet and glares at you. "What's this? What is happening here?" The dwarf asks, confused. 

"...Are you really going to free the gnoll? Don't you know how dangerous that is?" Mentha asks in disbelief, readying her crossbow. Nighthill sighs and once again asks everyone to please relax, but no one is having it. Everyone's too afraid and stressed out by everything that has happened for that. 

"I'm sure they have a very good explanation to do it" Nighthill reasons. Mentha glances at him and then back to Kane and Harmony. "Well, if there's an explanation, it would be really nice to hear it, ya know!" She says.

"Well, you see..." Ignar starts talking, but quickly shuts up when Mentha points the crossbow at him. "Quiet, cultist. We'll get back to you in a second."

Apparently scared of the menacing crowd and the tiny crossbow lady, Leyding stays inside the cage until finally told otherwise.

Kane gets between the cage and the villagers. “People of Greenest! I understand you are scared. Some of you have lost their homes, others lost the lives of people they loved. And many of you are angry. I understand. But do not unleash your angry in Leyding. She is a kind, sweet soul. When I was injured fighting these very cultists, she used her magic to heal me. But all you people see is a gnoll, a monster. If she bit or attacked any of you, you must have provoked it. What if you looked like a monster? How would you feel being poked and called names? I would know. I spend everyday of my life trying to change the stereotype of Tielfings, but I can only do so much. It has to start with people like you. You must not judge someone because that have fangs, or claws, or horns. You judge them on their action and their character.” He opens the cage and tries to convince Leyding to come out. “Please, people, she is completely harmless.” 
Persuasion: 14

*Seriously, after that great speech?*

"She's a child and she's afraid. Her only family member might have just been killed in front of her, and now there's a mob of people screaming at her. She's not the type to hurt anyone, but you can't blame her if she's a bit on edge right now," Harmony calmly explains to Mentha. While Kane is giving his speech, she steps into the cage, helping Leyding get out of the chains and muzzle. She picks her up and holds her protectively, eventually trying to make her way around the crowd and downstairs.

If she is able to make it down safely, she'll try and find some sort of side room or corner where there's a bit more privacy. She uses prestidigitation to clean the blood from Leyding's fur and clothes, then wraps the cloak from earlier around her. "You're okay. They're not going to hurt you."