Why did Randy move his family before he died?

The main reason Randy moved his family before he died was so that his wife (Jai) and their three children could be near Jai's extended family after his death.
Randy did not want Jai and his children to be without crucial emotional support during their impending bereavement. As a result, he packed up his family and moved them from Pittsburgh to southeastern Virginia a few months before his impending death.
Randy spent the last six months of his life making arrangements for his family's future. Interestingly, he also spent these months preparing for his last lecture at Carnegie Mellon University in Pittsburgh. When Jai questioned his motivation for giving this last lecture, Randy told her that he wanted his kids to be able to know who their father was when they were old enough (and curious enough) to ask. He promised her that his last lecture would be recorded for this very reason.
Additionally, Randy also wanted to know that, despite his cancer, he was still capable of doing the work he had always loved. His words to Jai were: "an injured lion wants to know if he can still roar."