Consider the species XeO3, XeF6, XeOF4, XeO2F2, BrF5, SF4, XeF4, XeF2, ICl4^-, ClF3, XeO4 and IF7. The number of species in which the central atom…

Steric number $=\frac12(V+M-c)$, where $V$ is the number of valence electrons of the central atom, $M$ the number of monovalent atoms (oxygen, being doubly bonded, is not counted) and $c$ the charge; lone pairs $=$ steric number $-$ number of $\sigma$ bonds. $\mathrm{XeO_3}$: $4$, 1 lone pair, $sp^3$. $\mathrm{XeF_6}$: $7$, 1 lone pair, $sp^3d^3$. $\mathrm{XeOF_4}$: $6$, 1 lone pair, $sp^3d^2$. $\mathrm{XeO_2F_2}$: $5$, 1 lone pair, $sp^3d$. $\mathrm{BrF_5}$: $6$, 1 lone pair, $sp^3d^2$. $\mathrm{SF_4}$: $5$, 1 lone pair, $sp^3d$. $\mathrm{XeF_4}$, $\mathrm{ICl_4^-}$ and $\mathrm{ClF_3}$ have two lone pairs; $\mathrm{XeF_2}$ has three; $\mathrm{XeO_4}$ and $\mathrm{IF_7}$ have none. Species with one lone pair and $sp^3d$ or $sp^3d^2$: $\mathrm{XeOF_4}$, $\mathrm{XeO_2F_2}$, $\mathrm{BrF_5}$, $\mathrm{SF_4}$, so the answer is $4$.