The way I've always seen it is that Dwarf and Dwarfs are the correct terminology when concerning reality, and that Dwarves only refers to mythical creatures. Calling a group of little people a gathering of dwarves is insulting to them. Dwarfs is correct, but even that isn't truly PC today.
This comment is wrong, to anyone reading. The medical condition for dwarfs is dwarfism and dwarfs is not offensive in English. "Little people" is quite patronising.
Yes, a general knowledge quiz must ask only about things with which I am familiar, and never, ever, teach me anything new! (Having said that, I think all the sports quizzes during their playoff seasons get a bit much. A few are okay by me, but not one or two every day for weeks, please.)