Dear student,

Mostly in all the NITs there is ews reservation.
As you have particularly mentioned the three states - Maharashtra, Karnataka and Andhra Pradesh, then here is the complete information.

In Maharashtra, the VNIT Nagpur has the ews reservation.
In karnataka, NIT Karnataka (also known as NIT Surathkal) also has ews reservation .

But in andhra pradesh if you opt for NIT Andhra Pradesh then it is one of the few NITs in which there is no  EWS category reservation .

Apart from nit andhra pradesh the nits in which there is no ews category reservation are :-

Nit sikkim
nit Meghalaya
nit manipur
nit mizoram
nit arunachal pradesh
nit puducherry
nit Nagaland
nit goa
nit delhi

So, all the other nits (excluding these 10 nits), have ews category reservation.