Darlene -
my mom moved in with me and my children for 6 weeks post op and like Adrienne's mom she was a lifesaver. I'm a single parent and I honestly couldn't have gotten through my surgery and my recovery without her, my father, and one of my sisters.
My children were 10 at the time and in 5th grade, so my mom's chief responsibilities were "managing" them and their schedules (homework, after school activities, etc.,) playing chauffeur to them - and to me when I had to go to a doc appt., and when I returned to work (before I started driving again) - and she was also the person who kept our household running. She did laundry, cooked, cleaned, etc.
I'd imagine that your daughter-in-law will take care of most of the household chores, but since she works you'll be instrumental in taking care of your young grandsons. Your son's biggest issues when he returns home will probably be balance and fatigue. Also, he may be sensitive to loud noises and he will have restrictions on lifting heavy things and putting his head below his knees (basically bending at the waist).
Being there for him - and for your daughter-in-law - is one of the best things you can do for him, in my opinion.
Jan