Hello student student there's only one government university in Delhi that's Delhi University, its not best only in Delhi its best across the country.
Some of the top Bsc college are mentioned below :-
Top 10 Science Colleges in Delhi University,
1)St. Stephen's College.
2)Miranda House
3)Hindu College.
4)Sri Venkateswara College.
5)Hansraj College.
6)Ramjas College.
7)Gargi College

Feel free to comment if you have any doubt
Good luck