During the hiatus of the series, both Rue McClanahan (Aunt Fran) and Betty White (Ellen Jackson) had both gone on to star in the NBC sitcom The Golden Girls, rendering them unavailable to return. White, however, did return as Ellen for one episode in 1986 while Fran was killed off in the first episode of the revival. Carol Burnett and Harvey Korman, meanwhile, did not reprise their roles either, resulting in their characters (Eunice and Ed Higgins) being written out as having moved to Florida.

Answer this question based on the passage: why did they kill off fran on mama's family? Okie... think carefully first, then make a decision:
The important part for answering this question is: During the hiatus of the series, both Rue McClanahan (Aunt Fran) and Betty White (Ellen Jackson) had both gone on to star in the NBC sitcom The Golden Girls, rendering them unavailable to return. So, the answer is Rue McClanahan ( Aunt Fran ) and Betty White ( Ellen Jackson ) had both gone on to star in the NBC sitcom The Golden Girls , rendering them unavailable to return.