There are many causes but frequent falls suggestive of neurological problems Get neurophysician consultation

There can be multiple reasons for this including knee problems, nerve problems or bone weakness. Consult with a pain management specialist for relief.

This treatment is being suggested   on bases of the information provided.  However I would like to examine & investigate your mother   in detail. -Control  Hypertension, Diabetes or  metabolic disorder, if there is any.  -Any way it may be tried, --. Dolokind Plus (Mankind) [Aceclofenac100 mg +Paracetamol 350 mg] 1 tab. OD & SOS. X 5 days. --. Caldikind plus  (Mankind) 1 tab OD x 10 days. -(You may need help of your local doctor to get these medicines.) --. Fomentation with warm water. Let the part not be exposed to cold. --. Sleep on a hard bed with soft bedding. --. Keep a pillow under the knees. --. Avoid painful acts & activities. -- .Do mild exercises for the back and lower limbs. --.(Take help of physiotherapist or you can visit my you tube channel 'Dr NC Gupta'.)   & see  me and my yoga; & yoga simplified. Kindly subscribe to the channel to get notifications for further new information of your interest.  --Do not ignore, let it not become beginning of a major problem. --Do ask for a detailed treatment plan. Kindly make sure, there is no allergy to any of these medicines. --For emergency treatment visit nearest hospital. --Wish you a quick recovery & good health. --I hope, I have solved your problem to your satisfaction.   Dr N C Gupta MS (ortho) DMC 3624  

Probably your mother suffered from neurological problems (like peripheral neuropathy ) Pls consult neuro physician

Get xray of knee and foot