Strongest oxidant among the following is

C⁺⁴ > Si⁺⁴ > Ge⁺⁴ > Sn⁺⁴ > Pb⁺⁴ stability order
C⁺⁴ < Si⁺⁴ < Ge⁺⁴ < Sn⁺⁴ < Pb⁺⁴ oxidizing power
For Pb +2 oxidation state is more stable due to inert pair effect and hence Pb in +4 oxidation state acts as oxidizing agent [Oxidant - electron gainer]
Pb⁺⁴ + 2e^- → Pb⁺²