The first time you play Granny handcuffs me in 'The Van', you'll notice a painting of her mom hanging off the wall. It is from the ending of the previous game, Slendrina: Asylum, and she hangs it in her room, which is a landscape orientation. This is indicative of a relationship between the two women - Granny seems to have a very adversarial relationship with Slendrina, and has a painting of her mother hanging on her wall.