Is there a caregiving place that will go into the home to stay with someone with dementia so the husband can work?

My niece has been sitting with her but she has told us she needs to get a job and can't till my mother has someone to stay with her. I've been asking family members for help to sit one day a week hoping that at least 5 will be able to but I'm not too hopeful on that because they work also as do I. My stepfather's health is not good either and the stress is making it worse, and he is taking care of my recently deceased sisters 20 year daughter who has downs syndrome who too has health issues and cannot be left alone. He needs help and we dont know where to turn for it. Also my mother has always had issues with anxiety and would not leave the house because of it, she goes outside around the house. but will not get into a car to go anywhere, she has not seen a doctor in over 10 years and she will not go. Is there someone who will go to the home to check her out? She has not been diagnosed as having dementia but the signs are all there. She is 75 and started showing signs of it a few years ago.