The production notes about what happened to Megan, Danny and Molly Williams after Discord threw them out from the world of Equestria/Ponyland and blocked the passage in the (failed) attempt to prevent the use of the Elements of Harmony: Molly spilled the beans to their parents, who, believing it had been a fantasy in which their children had been a little too much involved, convinced her and Danny that it had been just a story and, as she was a teenager, locked Megan in an asylum (from which she broke out in short order). The same notes mentions that she considers her siblings and parents dead to her.
