In which of the following molecules, the central atom does not have sp3 hybridization?

For neutral molecules,
Number of electron pairs = Number of atoms bonded to it + 1/2[Group number of central atom - Valency of central atom]
∴For CH4, no. of e⁻ pairs = 4 + 1/2[4 - 4] = 4 (sp3 hybridization)
For SF4, no. of e⁻ pairs = 4 + 1/2[6 - 4] = 5 (sp3d hybridization)
For ions,
No. of electron pairs = No. of atoms bonded to it + 1/2[Group no. of central atom - Valency of central atom ± No. of electrons]
∴For BF4⁻, no. e⁻ pairs = 4 + 1/2[3 + 1] = 4 (sp3 hybridization)
For NH4⁺, no. of e⁻ pairs = 4 + 1/2[5 - 5] = 4 (sp3 hybridization)
Thus, in SF4, the central atom does not have sp3 hybridization.
Therefore, the correct option is B.