Pear Butter is the mother of Applejack and a supporting protagonist in My Little Pony: Friendship is Magic. She and her husband physically appear in flashback in the season seven episode The Perfect Pear, which is where their story is finally told. They are alluded to in other episodes and media.
It is implied that before the series, Pear Butter and Bright Mac passed away, leaving their children under the care of Granny Smith