Family support is always an important key in patient recovery from any operation. Helping her at home during the early post-operative period is a good idea. The goal is to help the patient regain as much function and independence as possible. Don't do everything for her--just help her when she asks for help.
A post-operative exercise program has been shown effective. Patient motivation is the key here. Many people start out enthusiastic but after several weeks or months their interest fades and they stop doing the exercises.
There are several ways to support your mother in this area. Purchase a membership in a health club or other exercise group for her. Go with her and exercise together. A goal of 30 minutes of exercise at least three to four times a week is best. A program of strength training, aerobics, spinal stabilization exercises, and flexibility may be best.