Dear Vidhi,
Its really interesting to see that you want to go ahed with bsc hons and that too in maths.
Yes you can go for it without having physics and chemistry. The basic criteria in colleges like DU, Dehradun colleg, St. Stephen, Narseemonji is that you have maths in class 12th and you pass with a minimum of 50% in your board examination.
All the best. I hope this was helpful to you.