You can file a complaint in the Court of Magistrate under Section 209 for dishonesty making false claim in Court. Offence  is non-cognizable therefore police will not take complaint. Punishment for offence  is imprisonment to two years. File complaint producing the ex parte decree and death  certificate. Summons will be issued  to him and after he will be convicted.   

Depending on the location of Court that passed the decree you can file criminal complaint in criminal Court at Secunderabad of at Nampally, Hyderabad. But before filing complaint, the respondent need get the ex parte decree set aside on the ground of suit having been filed in the name of dead person. You can get it set aside as there is no limitation against decree obtained by fraud. 

If you are the defendant then you can file an appeal and challenge the case.

Since this is a court case decided on merits, defamation case is not maintainable.

If the plaintiff had committed any criminal offence then you can lodge a criminal complaint with police about it.

Without seeing the case papers and the court decision no further opinion can be rendered 

Section 209 of the Indian Penal Code makes dishonestly making a false claim in a Court as an offence punishable with imprisonment upto two years and fine.

2)file case against plaintiff under section 340 cr OC read with section 209 of IPC

Dear client,  I am sorry to hear that but in this case you can obviously file a deformation case.

Yes you can file 340 crpc against the said person for. Perjury and set aside the order too by filing a suit