which category can be equal to gen ews in normal engg clgs ??

See most of the government colleges have the reservation under the EWS category but there are very few private engineering colleges which avails this facility. Now if your college have the GEN-EWS reservation then its ok but if not then you have to go only for EWS as there are no other subsequent categories which you can click.

Now if your college offers scholarship or TFW(Tuition Fee Waiver Scheme) then you can apply for that and in general if your family have income less than Rs. 2.5 LPA then you will easily get this facilities (if available).

Again private colleges may have scholarship but there are a very few which offers TFW facility for students.

I hope this answer helps. All the very best for your future endeavors!