My friend has got all India rank 6.7k in jee mains.which is the best institute she can get with this rank in cs branch??(general category)

Hey , Greetings from career360 !
The all India rank 6.7k is pretty good score . You can predict the best college which you can using the following link . They actual result may vary slightly as this is based on previous year statistics https://engineering.careers360.com/jee-main-college-predictor?utm_source=google-search&utm_medium=paid&utm_campaign=jeemain-clgpd

Hey,
Congrats for such a wonderful score.
You have a good chance of getting into good NIT. You can check for previous year cutoffs of NIT's on the following link

https://www.google.com/amp/s/engineering.careers360.com/articles/nits-cutoff-for-top-btech-branches

For other available colleges with your rank you can check on the college predictor link provided below

https://engineering.careers360.com/jee-main-college-predictor

Hope this solves your query.
Good Luck!!