consider the following outcome:

liberals: 145
conservatives: 141
bloc: 30
ndp: 15
greens: 7

145 + 15 + 7 = 167.

you need 170 votes to pass a budget.

and, the last time the bloc agreed to vote for a liberal budget, they got creamed in the next election.

you could also imagine something like this, if the greens kill the liberals in swing ridings and the ndp hang on just enough:

liberals: 130
conservatives: 141
bloc: 30
ndp: 30
greens: 7

130 + 30  + 7 = 167, still. but, the governor-general may let the conservatives form a government, because the bloc are unstable. and, it would be the liberals that the conservatives would be looking to help prop them up.

it is pretty clear that the ndp are not going to rebound in quebec, and i remain exceedingly skeptical of the idea that the conservatives are going to make a breakthrough there. the liberals surprised everybody by over-performing in quebec in 2015, which is how we get here (most people, including myself, predicted a strong liberal minority rather than a weak liberal majority; it was a difference of 15 seats). it's really the liberals v the bloc, there.

unless - and i'll point out again that this is not impossible - the greens show up out of nowhere and sweep, which ironically could save the government. it's remote, but quebec does crazy things like this fairly frequently: they vote tout ensemble, and they do so in protest.