I think she's going to have to have seen troubling signs. Villages with no adult men except the aged. Or with no one. And it's going to have to be several days from the last place where they could sit and talk and hear all the rumors. Perhaps they will garner suspicious glances because (unbeknownst to them) they are taken for spies.
Or perhaps the refugee she meets fled very far. It would explain why the characters are so bent on traveling quickly, right up to the point when she tells them it's impossible.
