Is this legal?

My auntie has MS. It causes her to have bad memory issues and difficulties understanding. She asked me to go to her consultation with her at the doctor because she noticed every time she goes, she doesn’t fully understand what they’re saying or she forgets. When we got there, she told the lady at the front desk and one of the nurses that she has a disability and asked if I could go with her to talk to the doctor but they said I had to stay in the waiting room. Is that even legal? Like I know a lot of doctors offices don’t allow people in the room with you but even if you have a disability that makes you require assistance??