Water has a greater boiling point than hydrogen iodide as water has hydrogen bonds, whereas iodine only has permenant dipole-dipole interactions. Hydrogen bonds are stronger than permenant dipole-dipole interactions as the hydrogen is attacthed to a highly electronegative atom, and thus creates a large enough dipole to form a hydrogen bond. In hydrogen iodide hydrogen is connected to iodine which is only electronegative to form a dipole that creates permenant dipole-dipole interactions.
As intermolecular forces are stronger in water than hydrogen iodide, more energy is needed to overcome these interactions, thus the boiling point of water is greater.