Can i get good nit if i score 100 in jee main my category is obc-ncl

Your rank will be around 80,000 - 1,50,000 by various rank predictor's in general and in obc 17,000 -  21,000
I don't think so that you will able to get not at this marks. But don't loose hope you will able clear her main cut off as per obc category. You must prepare yourself for her advance and any other exams that you have filled. Some are available at this time so you can choose them like pessat,etc.

It's very difficult to get in good NIT with good branch.