S.E.
Oh snap this is bad. So, hubby won't even consider standing up for your privacy? How long did you live with them? Was it their house? Did you pay rent? There are lots of questions.
I would seriously hate this. But, (devil's advocate here) if you all already lived together for 5 years (!) then they probably don't se your house as off limits in any way and think that calling for a heads up is more than enough courtesy.
If you don't see it that way you need to think about how long granny is going to live and how long you can tolerate this. You lived with them for 5 years! Did you get along, was it solely for financial reasons? Either way this is a bit of your payback for living with them for so long.... If Granny's life expectancy is only a few months or even a year or so you may have to suck this up.
If its going to really drive you nutso you might want to see someone to help you sort out your feelings and what you think is a battle worth fighting - or not. The bigger issue is how you managed to live with them for five years if hubby wouldn't stand up for you.