There are many of them. Almost in every college, university or institution across India Mathematics is available in which you can do your Graduation. 

After Science you can go for BSc, BSc Honors in Mathematics. In every state there are private, government colleges. 

Well most of the colleges do not require any entrance exam some of them do require.

For example In Indian Statistical Institute a student must clear their entrance exam and interview to get admission for BSc Honors. 

If you still have any queries feel free to ask in the comment section down below.