6x2 - The Flintstones

When Wilma gets a letter from her mother saying that she is moving in with her favorite son-in-law and his wife, Fred begins refurbishing a dilapidated shack to house Mrs. Slaghoople. But soon Wilma learns that he mother was not referring to Fred, but her other daughter's husband. Fred is delighted, until he realizes how much he spent on the shack.