hi first to get proper assessment with ortho/physio and start walking for atleast 20 minutes,knee tightening exercise with proper knee support.

Definitely arthritis is severe plz make her understand that excessive exercises like sitting and getting of floor will deteriorate the joint and also improper use of musculature that may cause issues in management. Plz speak to your orthopeadic surgeon and plan if surgery is suggested it will be definitely helpful in this stage!

You should consult an orthopaedic surgeon who will examine her thoroughly and prescribe certain Xrays of the knee. The first line of treatment is usually physiotherapy, activity modification and anti-inflammatory medications.

You probably requires Total knee replacement