Career

That depend on the career you wish to pursue. If you aspire to become a CS. The company secretary is responsible for the efficient administration of a company, particularly with regard to ensuring compliance with statutory and regulatory requirements and for ensuring that decisions of the board of directors are implemented.
1. CA is a vital link between the company and its Board of Directors, shareholders, government and regulatory authorities.
2. A CS ensures that Board procedures are both followed and regularly reviewed and provides guidance to Chairman and the Directors on their responsibilities under various laws.
3. CS Commands high position in the value chain and acts as conscience seeker of the company.
If this is what you wish for yourself than you can pursue CS else their many option after B.com such as M.Com, MBA, etc.

Astro-physics is offered by IISc, Bangaluru beside, Universities that offer Astronomy & Astrophysics specialization at M.Sc., and in some cases, a Ph.D. programme are:-
Punjabi University, Patiala, Osmania University - Full M.Sc. Course in Astronomy & Astrophysics, Aligarh Muslim University (AMU), Allahabad, Bangalore, Burdwan, Kolkata, Delhi, Gauhati, Gorakhpur, Gujarat, Indian Institute of Science, Jadavpur, Kashmir, Kumaon, Lucknow, Madurai Kamaraj University, Mahatma Gandhi University, Kottayam, Pune, Punjab, Pandit Ravi Shankar Shukla University, Roorkee, Swami Ramanand Teerth University, Nanded.
Indian Institute of Astrophysics (IIA)
IIA has a full-time Ph.D. programme for which the students are selected through an entrance exam, followed by an interview. The exam is conducted in November every year and this is advertised around September. Students are also selected through Joint Entrance Screening Test, conducted annually in the month of February, followed by an interview. The advertisement appears in all leading newspapers. Posters are sent to various institutions, universities and colleges all over India. Highly motivated candidates with a M.Sc. degree in Physics / Maths or M.Tech. in Engineering & exceptional candidates with B.E. /B.Tech. degree and a good background in physics are eligible to apply for admission to the Ph.D. programme.

Well, both are good but if I have to choose one I will go with Engineering and that too in CSE. Computer Science will remain the most sought out branch for the foreseeable future. However, it is equally important to know, what interests you?
For CSE you should target for:
1. Bits – Pilani.
2. DCE
3. NSIT
4. BIT – Ranchi.
5. UPES – Dehradun.
6. UTM.
7. Thapar - Patiyala.
8. ISMU – Dhanbad.
9. UPTU Government colleges (HBTI, IET, BIET, MMM, KNIT).
10. VIT University.
All are good but among these UPES and UTM offers specialized CSE programs and have a number of specializations to choose from and all in collaboration with IBM. Admissions notice is already out so hurry up. Get the details from websites or Institutes and apply at the earliest.