The Naked Venus.

A young American painter and his French wife move with their small daughter to the US when the husband's father dies. His mother takes an instant dislike to the wife, and when she finds out that her daughter-in-law is a nudist who once posed naked for an artist, she declares her son's wife to be an unfit mother and sets out to break up the marriage--which may not be difficult to do, as the son is a weak-willed "mama's boy" who's terrified to stand up against his domineering mother.