The Lights Go on Again — Kit Pearson

For five years Gavin and his sister Norah have lived in Canada as "war guests." But now, as 1945 approaches, the war is finally ending, and Gavin and Norah will soon be going back to England.
Norah, who's fifteen, is eager to see her parents again, but ten-year-old Gavin barely remembers them. He doesn't want to leave his Canadian family, his two best friends and his dog.

Then something happens that forces Gavin to make the most difficult decision of his life.

The Lights Go On Again is the last book in the acclaimed series that began with The Sky Is Falling and Looking At The Moon.