Personally I think since your son & girlfriend are in early recovery; I would opt not to serve alcohol, and come up with some festive non-alcoholic drinks, including sparkling juices that you can serve in place of wine, etc.
The exception to this would be if alcohol normally plays a key role in your holidays, and your other guests do not know the situation with your son. That could make for some awkward comments, and make them feel like they ruined a tradition, etc. In this case, Id talk to your son in advance.
If they do know the situation, then I would think most people would much rather spend time with people they care about, and the issue of no alcohol for them would be trivial. For the most part, Id say if others have a problem giving up alcohol for a night or two; maybe they have a problem themselves !
While I don't think most people who abstain expect others to alter their behavior to accommodate them, I think that it is a very caring and considerate gesture. I also think there is no time like the present to establish new holiday traditions the whole family can enjoy; also showing your son he (and everyone else) can have a good time, enjoy the food, the beverages, and that the holidays can still remain incredibly special.