Hydrogen bonds are formed in many compounds e.g., ${\mathrm{H}}_2\mathrm{O}$, $\mathrm{HF}$, ${\mathrm{NH}}_3$ . The boiling point of such compounds depends to a large extent on the strength of hydrogen bond and the number of hydrogen bonds. The correct decreasing order of the boiling points of above compounds is :

The size and electronegativity of the atom affect how strongly hydrogen bonds with other molecules.
A smaller atom has a higher electronegativity, which makes its H-bonding stronger. As a result, H...F>H...O>H...N is the order of H-bonding strength.
However, each HF molecule is only joined to two other HF molecules, whereas each ${\mathrm{H}}_2\mathrm{O}$  molecule forms an H-bond with four more ${\mathrm{H}}_2\mathrm{O}$molecules.
${\mathrm{H}}_2\mathrm{O}>\mathrm{HF}>{\mathrm{NH}}_3$ is the order of decreasing boiling points as a result.