Well ... it's never really explained, but I could come up with a guess.
If you played the last game, you know that Lauren and Joey encountered the Countess when she was alive and killing people, and they killed her (in self-defense, but still). Either the Countess's ghost is unsettled by seeing the photo that reminds her of that event, or Auntie Lauren still has a presence in the photo that comes to Rosa's aid. In any event, she decides that all three of them need to go to the place between the worlds, where her former spirit guide, Madeline, shows up to complicate things further.
Or maybe Dave Gilbert prayed to Saint Deus Ex Machina, who leaned down and helped him get his heroine out of an inescapable trap. Who knows.