Dear Gupta ji..
Your father appears to be suffering from Chronic hepatic failure
secondary to long term alcohol use.
The symptoms listed by you along with the raised ammonia levels - indicate Hepatic Encephalopathy
Though it is also possible that he has gone into Alcohol withdrawal
delirium - however the fact thaT he has had recurrence of symptoms after recovery shows likelihood of encephalitis.
He will need admission into a hospital, low protein diet
, regular monitoring of ammonia levels.
Has he ever vomitted blood ( oesophageal varices) or passed black coloured stools ? Hidden (occult) bleeding with re-bsorption of same in the gut can also cause these symptoms.
Bottomline: get him admitted to a hospital where a team of physician + psychiatrist
works (as adviced by Dr Raghavendra above)