Motor vehicle tax exemption

My mother is 100% disabled and I do a lot for her in the house, go to the pharmacy, go to the doctor, shop etc. But the lady bim inch has made me unsure, can I not do private trips with it? What if I have to go to the workshop? Can’t carry my mother and wheelchair all the time up and down the stairs. Or if I take my mother to the workshop in the evening. Is there a page where you can read everything? Or if I go to the city and do errands for my mother? I just want to secure me.