Can I just say that is sounds to me like your husband is timing his recovery activities to use recovery as an excuse to avoid dealing with his grandmother? I agree with the other poster who mentioned that AA is available at other times of the day and he could easily find a way to do his recovery activities and help you out. But it sounds like he's using recovery to avoid being at home. That's not to suggest that he doesn't need recovery, but that he needs to be mindful of other areas of his life as well.
I speak from some experience here as I spent 7 years in a live-in relationship with an AA who did something similar-- he didn't want to deal with his issues so he used recovery as an escape. He never worked the program but pretended to. He was horrible at home, but everyone thought he was a hero in the rooms.