On his deathbed, Grampa makes a confession to Homer about the notes from Homer's mother that got lost when she left. This angers Homer to the point of refusing to reconcile with Abe after he miraculously recovers.
While at the demolition derby, Grandpa has a life threatening heart attack which he uses on his deathbed to confess to Homer the most dastardly thing he could have done to Homer while he was young. This turns the whole family against Grandpa. Will Grandpa make things right? Why is the diner serving his mothers recipe?—Movie Dude