B.Sc

You can go for M.Sc as after Master's degree, you will get good career opportunities.
Good luck.

You may get admission, but you will have to start from the beginning. There is no provision of offering direct admission to the 3rd year in DU.

Good colleges for forensic science are:
Gujarat Forensic Sciences University, Gujrat
All India Institute of Medical Sciences, Delhi
Lok Nayak Jayaprakash Narayan National Institute of Criminology & Forensic Science, Delhi
Lovely Professional University Jalandhar,
Jawaharlal Nehru Medical College,
Dr. Bhim Rao Ambedkar University Agra,
IFS India Education Department,
Osmania University Hyderabad,
University of Madras,
West Bengal University of Health Sciences, Kolkata
IFS Mumbai, Nagpur, Aurangabad,
NIMHANS
Osmania University, Hyderabad.
Dr. Hari Singh Gour University.
University of Madras.

Good colleges for forensic science are:
Gujarat Forensic Sciences University,
All India Institute of Medical Sciences,
Lok Nayak Jayaprakash Narayan National Institute of Criminology & Forensic Science,
Lovely Professional University-Jalandhar,
Jawaharlal Nehru Medical College,
Dr. Bhim Rao Ambedkar University-Agra,
IFS India Education Department, Osmania Universit-Hyderabad,
University of Madras, West Bengal
University of Health Sciences, Kolkata
IFS-Mumbai, Nagpur, and Aurangabad,
NIMHANS
Osmania University, Hyderabad,
Dr. Hari Singh Gour University,
University of Madras.

Top colleges are:
Gujarat Forensic Sciences University,
All India Institute of Medical Sciences,
Lok Nayak Jayaprakash Narayan National Institute of Criminology & Forensic Science,
Lovely Professional University-Jalandhar,
Jawaharlal Nehru Medical College,
Dr. Bhim Rao Ambedkar University-Agra,
IFS India Education Department, Osmania University-Hyderabad,
University of Madras, West Bengal
University of Health Sciences, Kolkata
IFS Mumbai, Nagpur and Aurangabad,
NIMHANS,
Osmania University, Hyderabad,
Dr. Hari Singh Gour University,
University of Madras.

IFS Mumbai, Nagpur and Aurangabad, are the best colleges. If you do not have any problem in relocation then you can explore other good options such as:
Gujarat Forensic Sciences University,
All India Institute of Medical Sciences
Lok Nayak Jayaprakash Narayan National Institute of Criminology & Forensic Science,
Lovely Professional University-Jalandhar,
Jawaharlal Nehru Medical College,
Dr. Bhim Rao Ambedkar University-Agra,
IFS India Education Department, Osmania University Hyderabad,
University of Madras, West Bengal
University of Health Sciences, Kolkata
NIMHANS.

Top colleges are:
Gujarat Forensic Sciences University,
All India Institute of Medical Sciences
Lok Nayak Jayaprakash Narayan National Institute of Criminology & Forensic Science,
Lovely Professional University-Jalandhar,
Jawaharlal Nehru Medical College,
Dr. Bhim Rao Ambedkar University-Agra, IFS
India Education Department, Osmania University-Hyderabad, University of Madras-West Bengal.
University of Health Sciences-Kolkata
IFS Mumbai-Nagpur and Aurangabad,
NIMHANS.

Yes. B.Sc. Maths (Hons) is a subject offered by IP College for women. The registration process is soon to begin probably from the next week. By the starting of June cut-off marks of the college will be declared. If you clear the cut-off you shall bring all the required documents and get yourself applied in the course.

According to your interest, you can choose best stream in B.Sc. But nowadays, B.Sc. Hons in physics is more demanding in India.