These compounds have been chosen with similar masses, to let you decide from their organisation.
You're supposed to look at effects that let molecules stick together more strongly, like electric dipole moments, or hydrogen bonds.
Though... Such reasons work not too badly for boiling points. As opposed, melting points are very hard to predict and depend hugely (100K differences) on tiny changes in the shape, so I'd tend to answer "found measurements, this is the order" and "because of experimental evidence" but this is probably not the desired answer.
This reflects in prediction software, that use sets of rules to estimate melting and boiling points of compounds. They are often 5-10K accurate on boiling points and 100K false on melting points.