Can a 23 year old with add and bipolar disorder be thrown out of the house with nowhere to go

My grandson has been living with his father and grandfather for about four years. My grandson and his grandfather had a dispute last night and was thrown out of the house for one night. He slept in his car and was allowed back in the house to take a shower and go to work with his father. Now, at the end of the day, his grandfather won't let him back in the house where. He can't even go in to get his morning and evening medicine. He sees an doctor and therapist once a month. Can they make him live in his car with no place to sleep, eat, shower, shave and no medicine. What can my grandson do to get help?