Is it legal that an aunt went to the doctor to get medication for grandma?

I do not fully understand the intention of the question, so I do not know what exactly worried you. I also have no knowledge about the real course of events and the relationship between my aunt, grandmother and doctor. So I can't pass judgment on the "legality" of issuing a prescription for dementia drugs. From experience, I can only say that carers of elderly people often go to the doctor, for whom a visit to the clinic is difficult to ask for prescribing medication on their behalf. If you have any reservations about the doctor's procedure or grandmother's treatment, it is best to contact the patient ombudsman with your question and a detailed description of the situation.