We had a family friend who had both hips replaced at once. In hind sight he would say it was too both to do at once. The recovery was almost 6 months. He was in a lot of pain for a couple of months.

Big picture this is a major opporation with an extend recovery. The good news is this seems to be an increasing common medical procedure. Perhaps see if you can get your mom some help and or visit during the initial recovery.

Good luck and good wishes to your mom!