Fair enough, I see where you're coming from and fully expect some proof. I do however have doubts that any proof will ever be conclusive enough to convince people and certainly not enough to get Modi to admit the truth if his govt is truly behind it. So what will providing proof accomplish anyway? Not providing proof might be a tactic to elicit lies that can be demonstrated as such through a trickle release of proof, enough to prove that the deniers are liars.
At the end of the day, Canada is a sovereign country and they are free to level a number of consequences against a foreign government if they so desire, including sanctions, visa restrictions, and so on. The only proof they need is for themselves, and to take action that will protect Canadians from foreign assassinations in the future. Canada really does not have to prove anything to India, especially if they do not believe the Indian govt is acting in good faith.