here is something on might vs. may. I got it while surfing net.
"So remember to use may when the outcome is likely and might when the outcome is less likely or uncertain. But also remember that you use might for everything in the past tense. Also, it's OK to use might when you're writing about negative outcomes, even if they're likely outcomes, if using may would make people think you were talking about having permission."
by looking at this "might" fits better here.
Yes rightly said ,consider following:
you may go to party !!! ORDER
You might go to party !!!! negative perception
You might beat him there!!!
so there is a difference in terms of tone and certainty too!!!
I think C here is more concise than A !!!
Its Now Or Never