How did Kelly's parents surprise her when they said they couldn't come to California for Christmas?

Kelly and her family had Christmas with her brothers in California. Her parents stayed in Philadelphia getting ready for George's first chemo session. Kelly was upset that her parents wouldn't be there. But Mary was firm. They were staying home. Her brothers and Edward understood. She was just looking out for George. It might be too much for him. Kelly knew she was acting like the kid who wanted a pony even though she was old enough to know her parents couldn't afford one. Kelly, Edward, GT, and Booker were at a friend's party when the doorbell rang and who walked in but Mary and George. It was a surprise for Kelly.