I would start by combing all of the bees together if you have not done so.
Dig through all of the dead bees to see if you see the queen, if not go through the hive and see if you can spot her.
If you have another hive that can spare a frame of brood WITH EGGS, give that to them. Wait for three days and see if they have made any queen cells, if not then the queen should be in the box somewhere.
I would first hunt for the queen, go slow and look for her intently, you are trying to find a needle in a haystack kind of thing.
Combine the bees in the nuc with the bees in the vac box, wait it out for a couple of days to see what happens even if you do not find the queen. Give them some syrup (1 to 1) to encourage comb production.
After three days go back through them hunting for eggs and/or the queen. You will need to look really hard to see eggs in the new white comb, get the sun to your back and let it shine down into the cells.
If no queen or eggs I would do a news paper combine with you other hive.
Another option if you are sure you are queenless, is to just buy another queen and introduce her to your new colony. I don't know if you have access to any in your area or want to spend the $$, but it is another option.