There's actually not much you can do.
Amount is small plus you did leave your Wallet alone (though in a Bag).
Maybe the other Passenger saw you using your wallet keeping it inside Bag and decided to get their hands over it once you got down at Kanpur.
Always carry your slick bag of small valuables with you. Even to washroom. Never put your...
more... wallet in your big bag.
Mine has all my TWS Pods (3 of them) with my Wallet and essential. Always keep all your Big Gadgets inside Bag Pack. And never use washroom when train is about to reach a halt.