my rank in her advance is 20200 , and 50000 Rank in jee main , I want CS which college will be better option for me, please suggest.

Dear student,

First of all congratulations that you gave your jee advanced exam.
Now as you have secured 20200 rank in JEE advanced exam and 50000 rank in JEE mains exam then you can get some nits but you cannot get any IIT.
Also you have not mentioned your category so I am assuming that you belong from general category. So as you are general category then including computer science engineering you cannot get any branch in any IIT.
Now as for the NITs, then yes, there is a chance that you can get computer science engineer branch only if you belong from home state of some of the lower nits.

If you belong from home state of some low nits then with your home state quota you can get cse branch in :-

Nit sikkim, nit Meghalaya, nit manipur, nit mizoram, nit arunachal pradesh, nit puducherry, nit agartala.

But, if you are some other state then there is no chance that you can get cse Branch in any NITs or IIITs or any gftis.

But with this much general category rank, you can get other colleges apart from nits and iiits, like HIT kolkata, Techno india university, hbti kanpur , or some other private institutions.

Also check out our JEE mains college predictor tool to get an appropriate idea of the colleges that you can get on basis of your JEE mains rank :-
https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer

Also use our JEE advanced college predictor tool to get an appropriate idea of the colleges at you can get on basis of your Jee advanced rank :-
https://engineering.careers360.com/jee-advanced-college-predictor?icn=QnA&ici=qna_answer