According to Jim Season 1 Episode 10

Cheryl’s mother is coming to visit them for Christmas and wants to stay at their house. Jim and Cheryl, however, prefer that she stayed at a hotel but don’t know how to bring it up without insulting Maggie. After Jim tells Maggie that Cheryl wants her in a hotel, Maggie gives her grandma’s pearl necklace to Dana. Cheryl’s upset and goes to the airport to ask her mother’ forgiveness, where she learns Dana only got the necklace because she doesn’t have anyone in her life like Cheryl has Jim. Meanwhile, the girls think Andy is Santa.