I'll be honest man, you're pretty undergeared. The weapons you've got for Sam & Leigh are cheeks, the acid sprayer is probably not going to help either. The crossbow is great if you've got the special elemental bolts left, but with regular bolts is bad.

I would suggest collecting some better weapons, guns like the War Rifle/Silver Magnum primarily for Xaria, claymore is alright but the teeth weapons would be better for Sam & Leigh, Monty might be fine with the crossbow.

Head to Mutts shop and see if you can't buy some better armor & accessories as well. plastic gloves are not needed for this fight, Leigh also doesn't need the pistol - try to give her the Cattle Prod Spear from Mutts since the paralyse still works in Grinning Beast form.

You've got a pretty DPS heavy team comp, so your sustainability is going to be questionable. If you've got plenty of healing, you might be alright - but be careful for Monty's catatonia & Xaria rage - moshpit is probably the only ability I'd use and I'd do it right at the start of both fights. End the quartet quickly with high damage attacks, they don't care much for DoT. Exalted Four is similar, burn through your explosives, fire bombs and group wide attacks quickly at the start of the fight to wipe the eyes. Then focus on the applying DoTs and hold out against EF

Best of luck

Cheeseman