Respected User, hi I evaluated your query thoroughly.
*Any neurological case requires detailed physical examination with sensory
  motor evaluations from all aspects ; relevant investigations of EMG , NCV,  
MRI , finding further reasons for underlying pathologies.
*After final diagnosis only line of treatment for outcome is decided & then
  comes prognostic issues.
*Till then - give him high protein, iron diet to boost up his immunity
  - light exercises at home.
  - avoid 
smoking / alcohol / any abuse substances if any.
  - avoid 
stress / 
anxiety.
  - have adequate sleep of 8 hours.
  - multivitamins , multiminerals , antioxidants , Methylcobalamine containg
    agents help to some extent.
  - maintain his hydration , BP , Blood sugar , 
Cholesterol levels.
 Hope this clears your doubts.
 Thanks for using Health Care Magic & reviewing my answer.
 Wishing your father a fast and speedy recovery from the same.
 Regards.
 Bye dear take care.