hey anshika 

the colleges you are talking about falls under delhu university . chosing one of them may be based on the personl preferences as well as the actual experience one has get . the ranking of gargi college is very good among all du colleges.but in my view which may be differ from others sri venkateshwar seems best for bsc maths honours . this college is famous for its maths course and ranking is also good .however research out some other factors as well 

best wishes