That is not really a necessity though?
Like if the Conservatives + Bloc managed to get a majority between the 2, wouldn't that be enough to get a Tory minority government through? In that scenario, the Conservatives do not need to win most of rural Quebec to get into power. They just need the Bloc to do it for them.
Or are the differences between the 2 parties impossible to bridge?
Bloc is not a natural ally for the Conservatives as they are significantly to the left. They are further to the left than Liberals, somewhere in the NDP ballpark. Policywise on an issue by issue basis Conservatives are closer to Liberals than they are to the Bloc. As such that makes any Conservative-Bloc alliance very awkward. They won't have much time for signature CPC policies like tax cuts and reducing the size of the government. That is not to say they won't support a CPC govt, they have in the past if they are pissed enough at the Liberals but it is not a match made in heaven and will require significant compromise from the Conservatives. Additionally being seen as the ones propping a CPC govt presents quantifiable risk for them as their base could start looking elsewhere- NDP did gangbusters in Bloc strongholds in 2011 so their voters are not shy about voting NDP.