Grandma Nussbaum is a recurring character who appears in a total of four episodes of Happy Days in Seasons 3, 10 and the series finale in Season 11.
In her first appearance, she is played by veteran actress Lillian Bronson. In the other three episodes, she is played by Frances Bay.
Lillian Bronson played Fonzie's feisty grandma in the episode "Fonzie Moves In" at the start of Season 3.
About Grandma Nussbaum
In the Season 3 premiere episode "Fonzie Moves In", Fonzie, in looking for a place for his grandma, shows her the room above the Cunningham's garage, as she moves in; when she desires a better place, Fonzie moves her into her own apartment, as Howard agrees to allow him to move in the room.
Eventually Fonzie and Grandma Nussbaum would move into a house together, by Season 9. In the Season 9 episode "Grandma Nussbaum", when Fonzie and Chachi, who are both concerned about their grandma forgetting things, as well as her eyesight and hearing not being what it used to be, try to convince the feisty granny to move into a retirement home after Fonzie talked to Howard's uncle Joe, who talked about how he liked it when he stayed in one at one time, as she convices them to change their minds when she has Fonzie try on her bifocals and hearing aid, as he, as she says "gets the picture".