Hybridization of central atom in NF3 is
We can approach this problem by two ways. Let's take a look at electronic configuration of Nitrogen.
Now why Nitrogen?
Because nitrogen is our central atom.
→ 3 Flourine will overlap with 3 sp3 hybrid orbitals.
→ In one sp3 hybrid oribital, a lone pair will be present.
So, sp3 hybridization
OR
By VSEPR, let's calculate electron pairs.
ep = V+L+A−C2 = 5+32 = 4
4 ⇒ tetrahedral geometry ⇒ sp3 hybridization