If this is the quest in Fort Joy with the missing daughter, who the guy says is dead, according to what I saw you are just supposed to tell her that - bang, quest finished.
That doesn't seem right though.
It seems broken, I'm pretty sure the daughter is the girl up those vines where you find Fane. Unfortunately, there are no dialogue lines about it ... which gives the girl no real purpose for even being there.
I'm pretty sure thats how the quest should continue, but it doesn't.