Boiling point comparison between cyclohexane derivatives
It's not the double bond in C that is significant here, it's the oxygen. The carbon-oxygen bond is polar and will make C more "electrically sticky" with its neighbors compared to A. Since the $\ce{O-H}$ bond in B is even more polar than the ketone in C, its boiling point will be even higher. Read more about it on this page.

(If you'd like to skip to the relevant section, on Google anyway, search "ketone vs alcohol boiling point".)