Hi there,
I'm in my third week post-op, and it really does get better. I was told to do clear fluids for the first six days, and then full fluids (i.e. your tomato soup or soup with 'no lumps, bumps, or chunks') for a week after. I drank broth and juice for the clear liquid phase. I also really enjoyed having 'pedia-lite' freezies. It's important to have something with electro-lites (sp?) in it, though gatorade has a lot of sugar.
I forced myself to walk up and down the hallway (apartment building) for the first couple of days, and I even did a couple of flights of stairs with each walk. The nurse advised the stairs, and I found that all my gas pain was gone in a couple of days. The problem is that my muscles cramped up horribly after that because I wasn't properly hydrated, but this got better when I drank more and took more of the pedia-lite (and gastralyte). Your pharmacist should be able to help your mom find it if you don't have any. So I'd recommend exercise, but make sure you're properly hydrated (and rub a535 helped too).
Good luck! And remember, it does get better.