what is the authenticity of the late death certificate in filling a case against the property?
You can challenge the death certificate, especially you can say that the RDO's death certificate is not valid especially since it was rgistered in the year 2015 with intention to grab this property.
You can argue that nothing prevented him from claiming the same within twelve years from the year 1987 if it was fake or fraudulent transaction.
What is the immediate action on dis issue?
Challenge his case properly on the basis of merits in your side.
How should i approach with the banker in misplacing the document?
You can get a certificate from the bank for this misplaced document held by them
How should i prove his father death was incorrect?
You have to procure evidence from your source or by cross examining him properly you can extract from his mouth that this is false document.
what is the impact of this case on my land?
No impact until it is proved that it is his property.
How the police will go on this court refereed case?
This is a civil case
shall i keep quite by considering it as silly case?
You have to challenge the case or else he may obtain exparte decree against your if he has already filed a suit before civil court.