Following Grandfather by Rosemary Wells illustrated by Christopher Denise

My seven year old son read this book to himself.  This is his review:
"Jenny, a little mouse, loves her grandfather.  She spends a lot of time with him.  Then he dies.   One day, after his death,  she goes to a restaurant and thinks she sees grandfather so she follows him and keeps thinking she sees him.  I liked this book because it is exciting because she keeps thinking she sees grandfather."
I think the ending confused my son.  Grandfather's spirit rescued Jenny from the ocean after he had died.  My son did not really understand that part as he said the story ended suddenly.
Points to discuss: death; Can a spirit really come back and help a person who is a live?
-Borrowed from the library.