Should land occupied at the end of wwii by the allies be returned to the nations that lost them?

It depends on the relationships with those countries towards the Allies. If it were countries that were neutral or against the Axis Powers, then yes, they should be. If they were at war with the Allies, than no, at least not all of it. Think about how Japan lost territory it had when Japan was defeated by the Allies (Basically America). They lost quite a bit of the islands in their possession, but not all their land. Other countries, that were neutral, and had gotten ran over by Nazis, had been returned to their respective countries at the end of the war because they weren't hostile to the Allies.

Yes. But wouldn't this be a matter of opinion?