So, the young girl ...
... when they met her in the woods, why was she there?
At first I thought she might have followed them, maybe to warn them, but she was wearing what looked like some kind of ceremonial cloak. So then I thought she might have been sent into "the curse" as some kind of ritual, a sacrifice maybe, to keep some sort of balance, but it was never mentioned and she wasn't seen again in the film.
So why was she there?
You might very well think that. I couldn't possibly comment.