Your mother's mother is your grandmother.
Your Uncle.
I call my mother mom
He is your uncle, in most families he would be Uncle (Jack, Fred or what ever his first name is).
You could call them as a brother/sister or as a cousin... If you're asking for yourself then good luck with that family.
That would be an uncle.
your uncle
Mothers brother ( uncle ) = amoo
You still call your brother, your brother.
You would call your husband's younger brother a brother-in-law.
Would you call your brother god?
Your brother's daughter would be your niece. So she would call you Aunt/Uncle
brother