When they arrived on the Applefarm, they didn't see anypony. They looked around but the Applefarm was empty. What happend?

Twilight came back from an exhausting day at Sweet Apple Acres and she just wantet to rest. But Spike had a long day to think about things so he had many questions to ask Twilight. Twilight got mad and used King Sombra's black magic to make him feel pain. Lil' Miss Rarity has also a little part in there :)