I'm about to play a grim hollow one shot in a few weeks,

We are level 14, so I'm looking for some help in creating a powerful character for this 1 shot as I think my DM is going to try and kill me (in a fun and light hearted way)

Party is 4 players, but I only know 1 other class which is monk  

Level 14, point buy

Any books as well as of coarse grim hollow

1 very rare, 2 rare, 6 uncommon and 5000gp 

If anyone has an idea please let me know

Well, are there any types of playstyles you are wanting to engage in with this character? Any class preferences? Do you know what type of DM you are going to have (such as rest lite, rest heavy, healing lite, etc)?

Character-wise, what type?

If you want tank plus nuker, go paladin. If instead you want tanky and sustainable damage, fighter tends to be better.

Are wanting to be highly specialized skill person and/or sneaky, rogue is best bet.

Magic thrower- go wizard or cleric.

Nature Caster, go Druid. If wanting more fighter elements with that, go ranger.

Can't figure magic items since there's too much blank space for me lol. Best of luck mate.

Driaz has pretty much got you covered,

I'd throw my weight behind pally. Tanky, bursty, self healing and access to radiant damage, what more could you want?

Paladin and Fighter tend to be your go-tos for "Tanks damage and deals a good deal back".  With that in mind; getting a +1-3 weapon or better yet; a +1-3 Flametongue or Sunblade are good options for magic weapons.  It sounds "boring" but with multi-attacking classes; that slight bump up in your average roll and damage per hit output starts to stack up over time.  Thing about 5e is never underestimate the power of tilting rolls in your favour.

Additionally; if you do go Paladin, don't feel that it has to limit your creativity when it comes to character building.  Paladins don't "have" to be the "lawful good holy knight" type: Oath of conquest, oathbreaker paladins can go pretty grimdark if you want.  Or I once made a concept for a lizardfolk paladin of the watcher; the ultimate in lawful neutral character.

Cleric = best class. Armor, healing spells, utility spells, buff spells, combat spells (who needs Sentinel when you can go Warcaster and upcast inflict wounds at 7th level as an AoO?) and the domains can customize/specialize your skillset while choice of deities goes to the RP angle.

paladin

+2 dwarven plate armor (very rare)

+2 shield (rare)

sunblade (rare)

+1 amulet of the devout (uncommon)

luckstone (uncommon)

cloak of protection (uncommon)

bag of holding (uncommon)

immovable rod x2  (uncommon)

this gives you25 ac, a bonus of charisma +2 to your saves, self healing, and good damage with smites and sunblade, which should give you good survivability

also immovable rod shenanigans

hope this helps

For Paladin:

1. 15 STR, 10 DEX, 13 Con, 8  INT, 10 WIS, 15 CHA, or dump dex and take 10 int instead (DM might take INT dumping into account and pull out the NASTY int save effects) or dump both and bump wisdom or con. If you take the belt of fire giant strength and don't care about potentially running into an anti-magic field: 8, 13, 15, 10, 10, 15 and take +1 DEX with the Slasher feat and +1 CHA, +1 CON with your racial bonuses.
2. Variant Human (Slasher +1 STR, Perception, +1 STR +1 CON)
3. Any of the Ravnica or Strixhaven Backgrounds (if the DM allows them, I know you said any book but that can obviously change lol) TAKE THE SHIELD SPELL IF YOU GET IT ON YOUR LIST SOMEHOW OR FROM THE STRIXHAVEN FEAT!!!!!!! Shield is better than silvery barbs, don't let anyone fool you. Don't get healing word, don't get good berry, get shield.
4. Vengeance, Conquest, Redemption, or Watchers oath
5. Defense fighting style
6. Sword and Board
7. ASI's if you don't pick up a giant belt: Skilled (Expert in Athletics, +1 STR); Heavy Armor Master; Athlete (+1 STR) or Resilient STR
8. ASI's if you get the giant belt: Skilled (Expert Athletics, +1 CHA); Shield Master or Fey-touched CHA (if you don't want to do Sword and shield. Get Gift of Alacrity, Silvery Barbs, Hex, or Hunter's Mark with this (if you don't get it from your subclass) and make sure that when/if you hex someone you give them DIS on strength or dex (depending of if they look fast/nimble or not)); Sentinel

Items (# means the rough order of recommendation): 

• Very Rare: Sword of the Paruns (1), Voyager Staff, Spellguard Shield (3), Peregrine Mask, or Belt of Fire Giant Strength (2 You won't have to spend ASI's on strength and can get all the OP feats)
• 2x Rares: +2 Amulet of the Devout, +2 Weapon, Boots of Speed (3), Cloak of Displacement (1), Cube of Force, Stirring Dragon's Wrath Weapon, or Stirring Scaled Ornament (2)
• 6x Uncommons: Boots of Elvenkind (gets rid of your dis), Winged Boots (1), Stone of Good Luck, Sentinel Shield(2), Guardian Emblem (5), Cloak of the Manta Ray (in case ya need to swim), Bag of Holding(IF someone else doesn't pick it up!!), Adamantine Armor (4), Winter's Dark Bite (If you want to be 2-handed instead of sword and shield), Sending Stones (6), Cloak of Protection (3), or Goggles of Night (if you don't have darkvision goes up to 2)
• Get plate and a shield with your money if you didn't pick a magic version of it here.

For Cleric:

1. 14 STR, 10 DEX, 14 CON, 8 INT, 15 WIS, 10 CHA if Twilight/Life cleric without mithral armor/giant belt. 8 STR, 12 DEX, 15 CON, 10 INT, 15 WIS, 11 CHA if you want to have at least a 0 for you bad saves and have a belt/mithral armor. 8 STR, 14 DEX, 15 CON, 8 INT, 15 WIS, 10 CHA if you don't care about int saves (can swap that with cha if you do) and went grave cleric.
2. Variant Human (War Caster, +1 WIS, +1 STR if the first array, +1 CON if any of the others, Perception)
3. Same as #3 for paladin. Refer to that one for this section. Although I recommend Silverquill, Prismari, and Quandrix over the other strixhaven backgrounds here because the others have much more cross over with the cleric spell list with the additional spells they give you.
4. Twilight Domain, Grave Domain, or Life domain.
5. Shield, no weapon unless it's a magical weapon with a passive effect or effect that you trigger with stuff like a reaction or bonus action.
6. Fey-Touched WIS (Gift of Alacrity or Silvery Barbs), Telepathic WIS (so that you can communicate with the party more discreetly) or Skill Expert (Expert Perception), +2 WIS
7. Cast spirit guardians 1st round, cast spiritual weapon the 2nd round and either dodge (if you didn't take the cloak of displacement) or cast toll the dead/sacred flame (probs sacred flame if you know there'll be lots of undead or fiends). 

Items (# means the rough order of recommendation) copy pasted but slightly different list from the paladin items: 

• Very Rare: +3 Amulet of the Devout
• 2x Rares: Boots of Speed, Cloak of Displacement (2), Cube of Force, Cape of the Mountebank, Stirring Scaled Ornament (3), and/or Belt of Hill Giant Strength (1)
• 6x Uncommons: Boots of Elvenkind (gets rid of your dis if you have it), Winged Boots (2), Stone of Good Luck, Sentinel Shield (1), Guardian Emblem (5), Cloak of the Manta Ray (in case ya need to swim), Bag of Holding (IF someone else doesn't pick it up!!), Adamantine Armor, Mithral Armor (4), Sending Stones (6), Cloak of Protection (3), or Goggles of Night (if you don't have darkvision goes up to 2)
• Get plate and a shield with your money if you didn't pick a magic version of it here (if you have the prof). Get MULTIPLE foci!! Get an emblem, get an amulet, get a reliquary, get a component pouch, etc. Just in case an enemy steals one or destroys one. :)

If your DM allows multiclassing just play a sorcadin or hexadin and follow some guide online.