Even creepier than wearing a mask of someone’s face is that this person’s lair (presumably “A”) is surrounded by photos of Alison. Yes, this was part of the regular lair, but it seemed more intense than usual — and eerily similar to Jessica DiLaurentis’s “shrine” to Ali in her house.
As soon as Alison’s mom came back to town, she moved all of Alison’s things back into the house and had a shrine of photos and memorabilia of her dearly departed daughter. Sure, she misses Ali, but this is more than a little creepy. Her sudden return already had us suspicious, and since we didn’t see her at Detective Wilden’s funeral, there’s a good chance she could have been hiding under that lacy black veil.