He can appeal against the said order before Appeallate authority in office or challenge the same under writ petition in hc. 

You have not stated he has admitted its only stated it has been proved by them.  If admitted willingly then there is no defence left unless stating that the admission was not voluntary

Dear Client,

Disciplinary proceedings cannot be Initiated or Continued after Retirement. He has been charge sheeted so what ever action or order will pass must before retire.

1. Disciplinary action can be taken on him any day without considering his date of etirement.

2. I am aware of a case wherein a PSU Branch Manager was dismissed the day he was going to retire. 

Hi, the criminal offence can still me made out against him .. The time period from which the offence has taken place has to be considered 

1. Once a person has been held for offence then there is no limitation or any restriction over to take any action against him.
2. Yes, as he has all the evidences against him, he can be surely dismissed subject to the saving all his retirement benefits till the final disposal of the case against him.
3. If he will be held guilty by the appellate court also then he may not be allowed to take any retirement benefits thereafter.

There is no bar or restriction in law  in dismissing or terminating the services of an employee just before his superannuation/retirement.

The delinquent employee  can approach  high court or CAT seeking an injunction or stay of dismissal order.

He can surely be dismissed a day before the retirement.