Hydrogen bonds are formed in many compounds H2O,HF, NH3. The boiling point of such compounds depends to a extent on the strength of hydrogen bond and the number of  hydrogen bonds. The correct decreasing order of the boiling points above compounds is

Strength of H-bond is in the orderH...F> H...O>H...N.But each H2O molecule is linked to four other H2O molecules through H-bond whereas each HF molecule is linked only to two other HF molecules.Hence, boiling point of H2O > boiling point of HF > boiling point of NH3.