legal hier right

Contact advocate as the facts reported by you may not be correct.  Take a legal heir certificate, death certificate and hand it over to advocate for doing needful for reopening/appeal and dismissal of the case.  Unless the facts are known, no one can offer guidance.  What is the relation to that transaction with legal heirs is the issue?  Whether summons was received for B, or in his name by B son is not known.  What was the case about is also not mentioned?   Only a local advocate can guide you suitably.