I think it is another way of getting all the property of Viranis.Since tripti would have come to know by this time that her signatures didnot match, she is trying a new way to get what she really wanted.MONEY MONEY MONEY
Babli would have died in the Party and she could be the one extra guestat the Party.Otherwise there is no reason why she is in Mumbai.The finger prints results are true as the one dead is babli and the one alive is Tripti.She might react in some different way once she sees ganga and could see her end too.