My mother wants him to stay with her, the father wants my child with him, and I want my son back with me, what are my rights?

Unless your mother willingly gives up her guardianship, you will have to go to probate court to have it dissolved. You are the mother so you have rights, but so does the father. You have not provided sufficient information, like, why your mother has guardianship, to further advise you, so I suggest contacting an attorney.