Hello,
I encountered the same bug during this quest, but it didn't corrupted my saved game.
Better is to let the helping village find the girl and tell you "here she is" before engaging dialogue, as ICantParry said.
Otherwise, you can let him help, and once he show you the right path (chich can be enough), talk to this villager again to say you don't need his help anymore, and then go engage the dialogue...