The single most important fact — which unfortunately goes against you — is this: the property stood in your grandmother’s name, and she herself signed the sale deed.
Under Indian law, title follows the name on the registered document, not the source of money. Even if every rupee of EMI came from your father’s salary, that does not make him the legal owner unless there was a written trust deed, benami declaration, or contemporaneous document showing that your grandmother was only a name-lender. Courts do not accept oral family understandings after decades.
Once your grandmother executed the sale deed in 2007: • the transfer became legally valid, • the buyer obtained good title (assuming the buyer was bona fide), and • the sale cannot be set aside merely because the money originally came from your father.
On the question of fraud or breach of trust by your aunts:
Criminal law requires proof of a legally enforceable duty and dishonest intention at the time of entrustment.
Here, the fatal legal problem is this: • Your father mortgaged the property to his sister informally, not through a registered mortgage deed. • There is no registered charge, no loan agreement, no written acknowledgment fixing a legal obligation on your aunt. • After your father’s death, the legal owner (your grandmother) chose to sell the property herself.
Because of this, courts will say: There was no entrustment of property in law → therefore Section 406 (criminal breach of trust) does not survive.
There was no false representation to a purchaser → therefore Section 420 (cheating) will not survive.
Even morally reprehensible conduct does not become criminal unless the ingredients of the offence are met. Courts are very strict about this.
On sending your aunts to jail — I need to be absolutely honest with you: There is no realistic criminal prosecution possible today that will survive scrutiny, especially: • the sale happened in 2007, • the legal owner signed willingly, • your grandmother never challenged it in her lifetime, • limitation has long expired, • evidence is oral and family-based.
Courts will treat this as a family dispute with moral wrong, not a criminal offence.
On getting the property back — that door is effectively closed. Any civil suit for declaration or cancellation is hopelessly barred by limitation (3 years from knowledge, even with minor extension). Being a minor in 1997 does not help against a 2007 sale that was never challenged for over a decade.
What might still be possible — but only in theory — is: • a civil suit against your aunts for recovery of money, not property, if you have any documentary proof (letters, witnesses, admissions) that sale proceeds were meant for your father’s family and were misappropriated. Even this would be an uphill task and likely to fail on limitation.
I know this answer is painful, but it is better to know the truth than be pushed into futile litigation. Indian courts protect registered title holders and bona fide purchasers, even when family ethics were violated.
If your goal is justice in principle, the law does not support it now.
If your goal is punishment, criminal law does not sustain it.
If your goal is closure, the healthiest legal advice is to let this go and avoid reopening wounds that courts will not heal.