Your mother would benefit from physiotherapy. I would advise the following:
1. 10 sittings of short wave diathermy.
2. Strengthening exercises for knee which she will have to continue life long.
3. Knee cap/knee brace depending upon her physical examination.
4. Ask her to avoid activities in which she has to sit on the ground, like puja, etc.
5. To use western toilet to avoid squatting.
Wishing her a speedy recovery.