Who is Grandma Mazur from Visions of Sugar Plums and what is their importance?

Grandma Mazur is the mother of Helen Plum, Stephanie's mother. Grandma Mazur moved into the Plum family home when Grandpa Mazur went to the great poker game in the sky. Grandma Mazur is in her 70s, mostly slack skin and spindly bones, with a mop of tight curly gray hair. It is apparent that Stephanie gets some of her personality from Grandma Mazur, who is irreverent and wacky, much to the dismay of Frank Plum, Stephanie's father.