The complexes with strong filed ligands absorbs the highest energy light than complexes with weak field ligands.

Ethylene diamine(en) is strong field ligand and ${\mathrm{H}}_2\mathrm{O}$ is the weak field ligand.

Hence, the correct order of energy absorbed is 

${\left[\mathrm{Ni}{\left(\mathrm{en}\right)}_3\right]}^{2+}>{\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\left(\mathrm{en}\right)}_2\right]}^{2+}>{\left[\mathrm{Ni}{\left({\mathrm{H}}_2\mathrm{O}\right)}_4\left(\mathrm{en}\right)\right]}^{2+}$