Did this quest, talked to the guard first and everyone got a journal update. One party member talked to the boy, think he got a journal update but rest of the group didn't, which told him all the necessary information. We killed all the monsters and found the girl which just said "Thank you for saving me" and nothing more. No journal entry update for anyone. Left, talked to the boy again and couldn't end the quest. Boy just pretended he never met us before. When I tried talking to him I got the message that "x is already doing this quest" x being one of my party members. He couldn't convince the boy his sister had been saved either.
:)