I fear that your hive has died from CCD, Colony collapse Disorder, caused by neonicotinoid pesticides.
CCD poisoning is odd, in that the pesticide is taken up in the middle of summer, and yet the hive shows no symptoms until a good part of the bees fly off in winter and die. The remainder of the hive is too small to move up to the food and dies from isolation starvation or it just dwindles away completely.
I would not feed the rest of the honey to other bees, as it might still contain some pesticide.
Take very good care of your other hives and try to figure out where the pesticide could have been applied.
Maize and canola are nearly always seed coated with it nowadays, and golf courses and parks often get a drench, which will poison trees and flowers for many months if not years.
If you can't stop the exposure it might not be possible to keep bees alive in your area in the long run, so please help to campaign for a ban of these pesticides.