NTA She should be grateful that you've stepped up for her son when she couldn't. He could have went into the system and she would have maybe never seen him again. You've given him a stable home and made sure his medical needs are taken care of.

The very least she can do is abide by your rules and respect you and your things while she lives in your home, and she can't even do that. Don't let her make you feel guilty for putting her son's need for a stable home before her wants. You're doing a great job, parenting for a grandchild is hard especially one with special medical needs. Keep your head up you're doing the right thing, and your daughter is being childish and self-centered.