Hybridization of iodine atoms in ${\mathrm{ICl}}_3$ (in its stable form, found in solid state) and  ${\mathrm{I}}_2{\mathrm{Cl}}_4{ \mathrm{Br}}_2$ are :

Hybridization of iodine atoms in ${\mathrm{ICl}}_3$ (in its stable form, found in solid state) and  ${\mathrm{I}}_2{\mathrm{Cl}}_4{ \mathrm{Br}}_2$ are Both $s{p}^3{d}^2$.

Hence, the option D is correct.