Your mother-in-law. Or, call her by her name.
You still call her your mother in law or if you were divorced you would call her your Ex- mother in law.
shivaji's mother call shivaji as shurba
You would call your mother's sister an aunt.
Your grandmother.
Your grandmother.
your great grandmother
your great grandmother
Your half-sister's mother may be your mother, if you have different fathers. If you have different mothers and your father is married to your half-sister's mother, then you probably should call her "mother." If your half-sister's mother is not connected to your father (i.e. her father married your mother) then there is no relationship name for you to call her mother, other than "my half-sister's mother."
In Bengali, you call your mother "āĻŽāĻž" (pronounced as "ma").
You can call her by her first name or if your comfortable some son-in-laws call them mom.
Your mother's mother would be your grandmother.