Hi, thanks for writing to HCM.
A detailed clinical evaluation is necessary to define the cause of her problem. Pain in her knees could be due to arthritic changes owing to her age. Whereas senselessness in the legs is definitely abnormal and suggests some neurological disturbance.
Senselessness in both the legs suggests some problem in her lower back (in the spine). An MRI
scan of the Lumbar spine
will help in establishing the culprit.
If she is a Diabetic patient, the senselessness could be due to peripheral neuropathy
So, it should be made clear whether her inability to stand or walk is due to Neurological problem or Muscle weakness
Vitamin D deficiency may lead to muscle weakness. Get a Vitamin D estimation done for your mother to see whether she is deficient or not.
Hope this information is useful. Good day