The oxidation state of Mn is +3 in this complex.
the outer electronic configuration is 4s03d44p0.
when CN6 comes it needs 6 orbitals but the available orbitals are 5 only (one S, 1 orbital of d as rest are filled with singe electrons and 3 orbitals of p).CN being strong ligand will make one electron of d orbital to pair with other d orbital.hence vacating one more orbital from d and total unpaired electrons in d will be now 2 and total vacant orbitals in d,s and p will be 6 which will be taken by CN6
so hybridisation is d2sp3 and unpaired eletrons is 2