Hey,
Here is the list of the colleges that offer B.Tech in Mathematics and Computing are as follow:
1. Indian Institute of Space Science and Technology,Thiruvananthapuram
2. Delhi Technological University,Delhi
3. Indian Institute of Technology,Madras
4. Jamia Milia Islamia,New Delhi
5. Indian Institute of Technology,New Delhi
6. Indraprastha Institute of Information Technology,New Delhi
7. Indian Institute of Technology Banaras Hindu University,Varanasi
8.Indian Institute of Technology,Hyderabad
For detailed information follow the link below below:
https://engineering.careers360.com/colleges/list-of-mathematics-and-computing-engineering-colleges-in-india
Hope this helps.
Good luck.

Ritvik, there are many good colleges in India offering the B.Tech Mathematics and Computing course and here I am providing you a list of some of those colleges:--

IIT DELHI

IIT GUWAHATI

DELHI TECHNOLOGICAL UNIVERSITY, NEW DELHI

NSIT, NEW DELHI

IIT HYDERABAD

IIT ROPAR

IIT GOA

Hope this helps you in making a good career choice and deciding the college which would be ideal for you.