For future reference, you want a photo of her and her mother in a frame on her nightstand in her room, and you want her to have a photo of yourself and her in her mother's house on her nightstand in her room.

And for years, teachers have been dealing with single-parent issues. Ask the teacher to help smooth it over if her mother hasn't provided a photo. The school probably all knows how the woman showed up at lunch every day & was causing problems... they know your daughter has special issues that will cause emotional trauma over her mother's odd form of caring. If the teacher is young & at a loss, ask for suggestions from the school counselor.