Part time kids can take 6 weeks or longer to adjust, especially if mom and dad are not doing the same things at home that you are. Ask mom and dad to PLEASE work with you. Get them to stay within sight at home, but not be catering to his every squeak and cry. Then they need to, as others have stated, try getting him to play in a playpen or some such thing on his own at times. I agree that she needs to get him adjusted to what goes on around him, and not expect his surroundings to adjust to him.
As for him not being ready for daycare; remember that it may not be an option for him NOT to be in care. If mom and dad have to work, then they will need to do something.
I feel very sympathetic, but I don't think you can speed it up in any way, other than just being patient and consistent. Best of luck!