You could lower the difficulty level of the game for the duration of the quest. It is a pretty tough one fot the point you're at.

I did feel when I first played that there were some clues--the smooth flattery of the lord himself in the Copper Coronet, his unwillingness to divulge anything until you showed up--the made this particular request for assistance sound like a setup. I consequently didn't take it for a good, long time.

An easyway to get rid of the Vampires TRAPS. Set 6 snares up the corridor from the vampires and the try to lure them out a couple at a time once they are dead reast to get back traps and then repeat the process Yoshimo would be ideal for this dont use special snares though they are Crap. Eventually the vampires should be dead

(P.S If your Trap setting skill is low and you keep failing to set a trap dont worry as you can rest after you have set one and it will still be there afterward so keep setting and resting until you manage to place 6 - They cause shit loads of damage)

If you can't kill the vampires why go there? You can avoid going to the vampire area. You just go left and the vampires stay in the area at the right, and if this doesn't work do it one by one with you're party. I went back to winspear hills to kill the vampires when i was a higher level. First clear your name and if you can't kill Firkraag yet, then do that a bit later to. Good Luck