M.A

To know about the fee you need to get in touch with the college officials. The details of fee structure is mentioned in the prospectus. The cost of the Application form+Prospectus is Rs.300/- .

PG Courses and further studies
B.Sc. Computer Science graduates may go for the following PG courses
MBA
PGDM programs
M.Sc. (relevant discipline)
Advanced Diploma (technical) courses

Please refer to the link provided below for details regarding different courses offered by Gauhati University. You can also download their brochure which contains accurate details regarding courses offered for study at the university:
https://www.shiksha.com/university/gauhati-university-guwahati-20039

After completing B.Sc in Zoology, you can look for M.Sc in Zoology/Applied Zoology. You can also try for courses in diverse areas like software or management. MCA degree is a good option for B.Sc students. If you have a flair for management, look for MBA or PGDM program. Short term courses in software offered by institutes like GNIIT or Oracle will be useful.

Few steps to start GATE preparation:-
1. Know your GATE exam syllabus
2. Select Best Reference Books
3. Prepare a study plan
4. Prepare own Preparation Notes
5. Practice Previous Question Papers
6. Practice few Mock Test Papers

Yes, you are eligible to take admission in B.Ed in the same university but not in the same year. After the completion of your Masters, you can apply for B.Ed. At a time, you cannot apply for two different courses either in the same university or different universities.