The 23-year-old Vani, who has been dividing her time between the Ladies European Tour events and the domestic Hero WPG, earlier won the fourth and sixth and was tied-3rd in the fifth leg.
Gaurika Bishnoi kept her lead at the top of the Hero Order of Merit as she logged her third straight second place finish. She continues to be the most consistent performer of the season with seven finishes in top-4 in eight starts, which include one win and three second places and two third places.
Amandeep Drall, who like Vani has also been playing on the Ladies European Tour, shared the second spot with Gaurika.
Smriti Mehra (73), Saaniya Sharma (71) and Gursimar Badwal (69) were fourth, fifth and sixth, while Tvesa Malik (72) and Neha Tripathi (74) shared the seventh spot.
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Sharmila Nicollet (73) was ninth and amateur Seher Atwal (74) shared the 10th place with Ankita Kedlaya.
Playing each one of her rounds with par or under par scores, Vani had three birdies and no bogeys for a flawless round and it was best card of the week.
Gaurika, one behind Vani at start, had two birdies and two bogeys and dropped a double bogey on the last, which cost her sole second place finish.
Amandeep's 72 included a bogey-bogey finish.
Amateur Ankita, bidding to be the first amateur winner this season, started one behind the leader. She began well with an early birdie but two bogeys on fifth and ninth meant she turned in one-over and with Vani turning in two-under, the gap between them was now four shots.