B.Tech Mechanical Engineering

No Chamraj,
It's only for the students upto class 12th.

After B.Tech in mechanical engineering, the career prospects are available in automobiles industry, production industry, maintenance and various other fields. The salary prospects are good in all the industries. You can try for L&T, JCB or automobiles like Honda, Hyundai, etc.

Go for M.Tech from any reputed institutions like IITs, NITs, IITMs or central universities. Appear for GATE 2017 and choose an appropriate branch.

Both are good, you should follow your intentions. If you are good at computer programming, it is better to take CSE. Otherwise, mechanical is much better.

Since you have already started studying in Swami Vivekanand Institute of Science and Technology, you must ask this question from your seniors. They will be better equipped and informed to answer this question for you.
My suggestion is that rather than worrying about placements, focus on developing your skills. Do new courses and learn about new technologies. When you are well prepared, you will not have to worry about placements from the college. You can get a job off-campus. All the best!

B.Tech Mechanical, Electronics and Aeronautical Engineering are preferred branches by DRDO and ISRO for Weapon and Spacecraft design and development. Pure scientists are also required by them, particularly Metallurgy experts.