Sir Roderick manages to take down one of the fleeing goblins in the dark, but the other one gets away, vanishing (to those with darkvision) around the corner ahead.

Everyone may act. (We'll assume Tessa and Bryony have caught up behind Quinn, unless they have other plans. Tessa has the light, but from way in the back, it does Sir Roderick in the front little good.)

Sir Roderick, I can add a light to your sword if you'd like (and the DM says my tinkering)

( sure)

Quinn is worried about triggering the wolves, so he continues to follow their lead without pressuring them too much. He keeps his eyes fixed on the wolves, to the best of his ability given the lighting situation, and he will swing at any of them with his axe if they act aggressively towards the party. 

Jurgen, still carefully holding on to the swaying rope bridge 20 feet over the rushing water below, takes a moment to add a magical tinkerer's touch to Sir Roderick's longsword. It's not very bright, but it will be enough to keep him from falling down a hole, and when the time comes, to melee.

Is the rest of the party continuing to move forward down the passage the goblin was fleeing down?

Sir Roderick soldiers on...

Perception- 16

Bryony sticks close to Tessa near the rear of the party. She doesn't want to rummage around in her own pack for a torch. She follows Sir Roderick's lead, silently marveling at how many goblins live in the cave.

Sir Roderick can see little beyond the tip of his own sword, but Jurgen and Syzygy, right behind him, can. They see that the corridor opens up into a large cave, divided in half by a ten-foot-high escarpment. A steep, natural staircase leads from the lower portion to the upper ledge. The air is hazy with the smoke of a cooking fire, and pungent from the smell of poorly cured hides and unwashed goblins. Eight goblins are present, including the one you chased in, together with a bound, wounded human prison on the southern ledge. The goblins shout over each other in alarm.

We're still in Initiative:
R Quinn 17
   Sir Roderick 16
   wolves 15
√ Jurgen 14
  Tessa 14
  Bryony 12
  Syzygy 6
  Goblins 4
  Two big javelin-wielding goblins: 13

Everyone has used their movement to get here. Jurgen has completed his action, and Quinn has readied one. 

Sir Roderick and Tessa may act next.
(...Although Tessa can't see what's ahead yet. ...nor can Roderick see the goblins. But he can hear and definitely smell them. He's also out of movement, but may take a ranged attack at disadvantage if he chooses.)

As he rushes into the new chamber, Sir Roderick can hear the goblin he has been chasing shouting ahead in the dark, together with a jumble of other voices, and he can see the dim embers of a dying cooking fire, but little else. Jurgen and Syzygy can see the whole scene ahead.

Jurgen can also see another passage leading steeply downward to the east, toward the stream. The passage is choked with rubble and interrupted by steep downward escarpments. 

Syzygy can see that the human prisoner has been badly beaten, and is barely conscious.

Sir Roderick and Tessa may act (but not move) next (but neither can see what lay ahead.)

Sir Roderick takes in the expansive darkness and the smells and sounds of goblins and steps sharply to the side to let others past.

" Right! You are all under arrest by the authority of Queen Raedra Obarskyr of Cormyr and the uh....Harpers and probably quite a few other interested parties for the crimes of robbery, thievery....murder......assault......kidnapping.......animal cruelty.....keeping protected wildlife without a license......uh.....vandalism....highway robbery......and general annoyance."

" If you all throw down your weapons and come along quietly I will speak favourably of your cooperation."

He looked out into the dark.

" Your leader Klarg.....Klog.......chose not to take me up on my kind offer, I suppose one of you is in charge now."

Intimidation- 23

There is confusion in the room as the goblins shout over one another.

One goblin lets loose their bow in the dark.
Shortbow Attack vs. Sir Roderick: 17. Hit: 8 piercing damage.
One of the wolves begins to bark.

"Hold!" shouts one of the large goblins in the back, in Goblin, to the others.

The other big goblin shouts back, "Bring us Klarg's head, then."

Tessa, Bryony, and Syzygy may act next (and anyone may respond verbally.)

The wolves trailing and sniffing behind Syzygy’s ass make him nervous. He hears an arrow slice through the air accompanied by the sound of goblin grumbles and hoots. “Gundren isn’t here” he hisses to his companions in frustration as he peeks into the darkness. One of the wolves begins to bark. “I’m done with, and dealing with the dogs. I’ll be back soon if things go south.” Zyzygy nervously retrieves the rest of his rations holding them high above his head, backtracking and squeezing beside Quinn, Byrony and Tessa, luring the wolves toward the bridge. 

Animal Handling 18+1=19

Sir Roderick looked down at the shattered arrow and stayed silent feeling incredibly lucky that that had worked to any extent....

Quinn hugs the wall giving Syzygy and the wolves space to pass. He hears the call from some unseen goblin to present Klarg’s head.

He grips the shaft of his axe so tight that his knuckles pop. Quinn the shouts back…in goblin.

Quinn runs to fetch the trophy. He stands tall above the body and hacks his head clean off with his battle axe. He will rush back with the head to present it to the goblins.

(DM: not sure how many rounds this will take, if we’re still in initiative. Let me know if I need to make any rolls.)

Syzygy manages to keep the wolves calm and successfully leads them back toward the rope bridge. (Then what?)

Quinn lets the wolves pass before passing them again, hurrying back across the bridge toward Klarg's Cave, feeling his way through the darkness. (It'll take him a few beats to get there and back.)

Sir Roderick continues to squint into the darkness, still seeing little past the tip of his longsword. But he can hear six taut shortbows drawn in the darkness in his direction.

But Jurgen can see everything. "So Klarg's really dead, eh? In that case, you can have this sad goat for a mere 500 gold." The big goblin kicks the prisoner in the ribs.
The prisoner looks up in Roderick's direction, and adds, groggily, "Don't trust him..."

Combat is paused; everyone may act. Tessa and Bryony have caught up with Jurgen and Sir Roderick.

Jurgen will advance with his dagger, cast green flame blade and strike the nearest one. 

Attack: 24 Damage: 7

if a goblin is within 5’ it takes 5 fire damage 

" Uh....", says Sir Roderick as Jurgen slashes. " Well, thats torn that."

He braces himself to be transfixed with arrows and charges forward into the dark standing guard over the prisoner.

Attack on any goblins that come close.

Attack: 14 Damage: 7

Jurgen cuts down the first goblin in his way, the one they had chased all the way from the Twin Pools cave. (There are no others within five feet to ignite.)

Sir Roderick charges in blindly toward the boss' voice, only to discover a steep escarpment blocking his way. Following the edge of the ten-foot ledge, he climbs a set of stairs he finds, and swings at the goblin at the top of it. It barely deflects his glowing longsword with its banged-up shield.

The second big goblin, a tough-looking brute wearing a chain shirt, throws his javelin at Sir Roderick as it begins to approach with its gleaming scimitar. (Sir Roderick can barely see it in the gloom, even ten feet distant.)
Javelin Attack vs. Sir Roderick: 11. Hit: 3 piercing damage.

The first big goblin, an even tougher-looking specimen, grabs the prisoner by his neck and dangles him over the top of the low cliff. "HALT! Or this human dies! Bring me that HEAD!"

Unaware of the new hostilities, Quinn dashes blindly through the cave system, eventually making his way into Klarg's cave, where he can dimly make out the dead king on the floor. (He may act to remove the head next turn.)

Tessa and Bryony may act next, as may Syzygy, who is occupied on the bridge trying to distract the wolves, but can hear the renewed fighting behind him.

Tessa creates a Minor Illusion of the Head lying on the ground in front of her and steps up, illuminating the room and head. 

"Boys! Let's back off a bit before anyone else gets killed. And you lot, if you want this head put down your weapons and we'll chat."

I hope this buys enough time to get the real thing, or at least get everyone together.