Suppose a compound contains atoms A B and C. The oxidation number of A is +2, B is $+5$ and C is -2. The possible formula of the compound would be :

Given the oxidation number of $A$ is $+2$ $B$ is $+5$ and $\mathrm{C}$ is $-2$

${\mathrm{BC}}_4$ has charge $=+5-2\times 4=-3$

$(BC{)}_4$ has charge $=-3\times 2=-6$

$A_3$ has charge $=3\times 2=6$

Since chemical is always neutral, its oxidation number is zero each atom has a net oxidation number of  zero. The compound is  $A_3{\left(B{C}_4\right)}_2$.

Hence, option C is correct.