Complex sentence: Nearly two decades would pass before the character was again reprised in the reunion film "Return to Mayberry" in 1986, by which time Fife had moved back and become the town's acting sheriff.
Split into simpler sentences: Nearly two decades would pass before the character was again reprised in the reunion film "Return to Mayberry" in 1986. By then, Fife had moved back and become the town's acting sheriff.