Noztrialez,
I just did this last night. It's not just a matter of killing off the Hook Horrors. I originally, cleared out everything but the Jellies b/c of their splitting ability. I kept going back and talking to Braud, but couldn't get anywhere either. I then went back and killed the Jellies (which took for freakin ever) and I then I got the option to tell him they were all dead and was rewarded (xp, no montary b/c of solo Monk). He then asks another favor of you
P.S. In one of the rooms, there are a ton of fire beattles. I don't know if you have to slay them to complete this quest or not, but I had before I talked to him originally.