I feel that there must have been a look alike Tripti, who is Babli, must have been her separated sister or so.
Tripti must have killed her and taken her place, so that everyone thinks that Tripti is dead. This she must have done at the party where she would have called Babli also.
Real Babli must have tried to write Tripti Virani Killed her, which Tripti must have scratched her name off to implicate Viranis.
She might have planned to double cross Rishabh also to be sole owner of the property, hence she must have plotted this, without knowing that her signature didnot match. Once she came to know that she preferred to remain Babli so that she is not caught at all.
So the dead body found must have been Babli and not Tripti.