How did Billys parents react when he came home?

When Billy finally heads home to face his parents and feed his puppies. He sees his lamp-lit home in a new way now, clean and neat and peaceful. Seeing the pain and worry leave his mother's eyes as he enters, he buries his face in her lap and weeps. His father has spoken to Grandpa and so has presumed Billy went for his pups. The family's pleasure with the gifts helps him recover his composure.