The Munsters' Revenge (1981) http://www.imdb.com/title/tt0082778/
The owner of a wax museum has an exhibit dedicated to the Munsters. When he uses robots that look like Herman and Granpa to pull a jewelry heist, everyone thinks that the real Herman and Grandpa did it. They must prove their innocence and uncover the real thieves.
Fred Gwynne ... Herman Munster
Al Lewis ... Grandpa Munster
Yvonne De Carlo ... Lily Munster (as Yvonne DeCarlo)
K.C. Martel ... Eddie Munster
Jo McDonnell ... Marilyn Munster
Bob Hastings ... Phantom of the Opera