Is there a large closet or bathroom within the master bedroom? If so, I would send the family in there while I stood watch over the locked bedroom door. Consider giving a loud verbal warning that you have called the cops and whoever it is should leave immediately. At the first sign of trying to enter the bedroom, I would open fire. While a bedroom door may not be much cover, it is a good "line in the sand" that I can dare anyone to cross.
I think they already crossed that line when they broke into his house, don't you? Why trap and barricade yourself in some bedroom if he could safely scare away or take out the threat if he had to from the stairs?
My Lord... at what point are we finally allowed to act to defend ourselves and our families in our own homes?