What is Finn's Mom name and his brother's name.Mom the human not Margaret. Not Jermaine too

we can't say because we don't know what his mother's name is in his actual universe and we don't even know if his mother had two children in this universe. so we can't affirmatively say what their name(s) is (are) or if they even exist. aside from the mother, who has to exist.

Multiverse. Different possibilities and different stories.

They never said what his mom's name is...