It's entirely possible that you lost your queen (as you thought) late in the fall and you may have simultaneously had an issue with varroa-vectored diseases. Since you had workers dead in the pile of dead bees, the queen must have made some winter brood but the drones in November is a pretty good clue that you had a drone layer or a laying worker right after that. Was the worker brood cell surface nice and even (flat appearance) or was it knotty with some cells protruding out past others? The later situation indicates that there were only unfertilized eggs deposited in worker cells because a drone developed in the cell and the workers had to increase cell length to accomodate their larger body size. Queens will put unfertilized eggs only in larger diameter drone cells unless she runs out of sperm or if she dies and you have a laying worker take over. You may only see knotty areas in small areas of worker brood comb if the end was near about the time brood production would slow down at the end of summer to early fall.
