Hello Arnab

There is no limitation in the number of choices for colleges in neet counseling . You are allowed to choose as many colleges as you want and also there is no limitation of course.

You are allowed to choose for MBBS colleges as well as  BDS  colleges. 

But be careful about the order of choices because the order given by you decides the college you get on the basis of your marks. More number of choices inhances the chance of getting  a seat in any college.