What was the name of Wilma's mother?

Wilma Flintstone’s mother was Pearl Slaghoople.

Pearl is portrayed as Wilma’s strong-willed, hard-to-please mother and Fred Flintstone’s notoriously difficult mother-in-law. She also becomes Pebbles Flintstone’s maternal grandmother, placing her within the central Flintstone family tree.

Pearl’s recurring visits often create comic tension because she disapproves of Fred’s behavior and schemes. In “Mother-in-Law’s Visit,” she briefly reconciles with Fred before becoming angry after discovering that he tricked her out of money intended for Pebbles’ crib.

A related continuity wrinkle concerns Wilma’s own maiden name. Some early episodes call her “Wilma Pebble,” while later stories use “Slaghoople,” derived from her mother’s name. That inconsistency does not change the canonical answer to this question: Pearl Slaghoople is Wilma’s mother.