I have 50 marks in her mains which good engineering colleges I can get admissions

Dear Sandeep
Those marks won't get you to be in IITs. So it's better to use those marks in private engineering colleges. It's my opinion.

Forget NIT's and IIIT's if you are not from some reserved quota. Check possibilities of some State govt. College or private universities which guarantee you a seat on the basis of your Jee main marks like NiST Berhampore, Gandhi,etc.( ODISHA) ,Heritage,Future,ITM University etc.
If you secured extremely well in your Class XII exams(85% + ...or 93% +) then you can also consider Amity University as they have a full fleged scholarship scheme.PS: Amity CSE is good.Do consider it.