The answer would be C. both, it would call the mother grandma cause its her son's child and mother cause the baby came from her as well, brother because they are both the mother's children so they are bros, dad because that's the father of the child.
unless they never told anyone or the baby that that is your brother or never said it was the babies brother than mom and dad to be realistic you would not call them both that's weird think about todays society. But the correct answer is A.
