One s orbital and one p orbital of silver mix and undergo sp hybridization to form two hybrid orbitals which overlap with appropriate orbitals of two ammonia molecules.
Hence the correct option is B.
$(I)\, [Ni(CN)_4]^{2-}\,\,\,(II)\, [NiCl_4]^{2-}\,\,\,(III)\,Ni(CO_4)\,\,\,$
$(IV)\, [Ni(H_2O)_6 ]^{2+}$