Hi, Hope you are doing great.
The best government colleges for taking admission into B.sc Maths(honours) are as follows:

Hindu College, Delhi

St. Xavier's College,Ahmedabad

Presidency College , Chennai

Government Arts College, Coimbatore

Farook College, Kozikode

Samrat Prithiviraj Chouhan Government College, Ajmer

Serampore College, Serampore

Panjab University

Hope it helps.
Thank you

The two best places in India offering Bachelor's degree in maths are the - Indian Statistical Institute and Chennai Mathematical Institute. Some other colleges are- Presidency University Kolkata, Madras Christian College, Loyola College Chennai, Jadavpur University Kolkata, Stella Maris College Chennai, Hindu College Delhi etc.