My best friends dad has a live in caregiver (no angency) she loves to argue with him because "she is never wrong"

She talks him into buying things for "his house because he needs them" such as a pressure cooker (he can't see so does not cook) has him buying memory foam pads for the chairs so she can sit more comfortably, told him he needs to buy her a better bed for her room because the one there causes her pain. She has guilted him inot many different things. Is there a law in California protecting him from this.....creature!? We suspect she may have taken stolen items to her daughters but can't prove that. I told them to take inventory of EVERYTHING with her present.