Bond strength is inversely proportional to the bond length of $\mathrm{E} - \mathrm{H}$ bond of hydrides of 16th group hydrides. The bond length increases down the group. Hence, bond dissociation enthalpy decreases down the group.

Hence, bond dissociation energy of $\mathrm{E}-\mathrm{H}$ bond in hydrides of group 16 follows the order

${\mathrm{H}}_2\mathrm{O} > {\mathrm{H}}_2 \mathrm{S} > {\mathrm{H}}_2\mathrm{Se} > {\mathrm{H}}_2\mathrm{Te}$.