What is the hybridization of cation of ${\mathrm{XeF}}_{6 }$solid?

The cationic part of solid ${\mathrm{XF}}_5$​ contains ${\mathrm{XeF}}_5^{+}$. In the cation, the central $\mathrm{Xe}$ atom has 5 bond pairs and 1 lone pair. Hence, it undergoes ${\mathrm{sp}}^3{\mathrm{d}}^2$ hybridization to form distorted octahedral geometry.

Hence, the correct option is B.