Which of the following complexes will show the largest splitting of $d$-orbitals?

The Crystal Field Stabilization Energy $(CFSE)$ and magnetic moment (spin-only) of an octahedral aqua complex of a metal ion $(M^{2+})$ are $-0.8\, \Delta_{0}$ and $3.87\, BM$,respectively. Identify $(M^{2+})$:

Which of the following comparisons is correct for the crystal field splitting energy $\Delta_0$ of the following complexes?
$I$- $[Co(H_2O)_6]^{2+}$
$II$- $[Co(H_2O)_6]^{3+}$
$III$- $[Fe(H_2O)_6]^{3+}$
$IV$- $[Fe(CN)_6]^{3+}$

Given below are two statements:
Statement $I$: Among $Zn$, $Mn$, $Sc$ and $Cu$, the energy required to remove the third valence electron is highest for $Zn$ and lowest for $Sc$.
Statement $II$: The correct order of the following complexes in terms of $CFSE$ is $[Co(H_2O)_6]^{2+} < [Co(H_2O)_6]^{3+} < [Co(en)_3]^{3+}$.

The crystal field stabilization energy $(CFSE)$ of $[Fe(H_2O)_6]Cl_2$ and $K_2[NiCl_4]$,respectively,are

The crystal field stabilization energy of $[Co(NH_3)_6]Cl_3$ is $......... \Delta_0$