The correct option is B [Cr(en)3][Ni(CN)5H2O] : Triethylenediammine chromium(III) aquapentacyanidonickelate(II)
We should be able to tell right away that option (b) is incorrect because there are three en groups and if multiple en groups need to be named with a bis or a tris but here its given as tri!
The correct name of this compound would be Tris(ethylenediammine) chromium(III) aquapentacyanidonickelate(II).