First of all congratulation and best wishes to all of you for your respective achievements. After discussion with different guys and analyzing few things mentioning answer of some FAQ -->
Q.-> should I join PSU or M.Tech ?
Ans. -> If you want job security, work life balance(It may not be there in organization like ISRO for few years), can remain happy with less pay and monotonic work OR you are facing some kind of problem OR need some small break (because GATE score card remain valid for few Years) OR want to explore something different (like you want explore your hobbies which needs good amount of time for example you want to prepare for UPSC CSE) OR want to prepare for much better university like MIT, Stanford etc then PSU could be joined.
Now even after doing M.tech also you may join some decent private/government organization job (in private sector pay will be high but sometimes work life balance may not be there) OR go for p.hd OR if you want less work decent pay and work life balance kind of job and want to live near to your home town then you becomes eligible for assistant professor job in most of the government college.
Q.-> Which institution should i join. Which one is better ?
Ans. --> First decide very clear goal (means why do you want to do M.tech ?). Now check whatever do you want to learn or explore in 2 Year time. Once you are clear that you want to become expert in X or Y, then check professor in India who is expert in that subjects. Accordingly institution could be selected. For example you want to learn stuff related to compiler then you can check who is offering this subject in different institutions and do you like whatever course content is delivered by him/her (respective professor research work could also be checked). Or create your own list of parameter based on your goal verify these parameter with respect to various institution.
Q.-> Which institution is good in terms of placements ?
Ans. --> All IIT and IISc are in general equivalent. But in IISc on campus recruitment for foreign countries is not allowed (Because IISc thinks you should deliver something back to your country). But in IISc if you want to get placed in some foreign country then off campus could be tried. One more thing almost all the companies have their office in Bangalore. So if your professor/senior refers you on Day -1 then on Day - 2 you will be placed in respective company.
Q.-> I am very clear that i want to do M.tech. But i have time till July. So should i learn something ?
Ans. -> Relax and spend time with family and friends, prepare your self to take next gear. Now you can learn many useful things from Coursera, MIT OCW, NPTEL, edx, edureka, etc. For example if you have decided that you want to learn stuff related to machine learning then you can learn various relevant things in that area from mentioned websites.
Develop good coding skills it will help you in placements in most of the companies and also it will help you completing various programming assignment quickly. If possible try to contribute in some simple open source software like Firefox, VLC etc.
Solve Cracking the coding Interview and review some most frequently asked problems in good product companies( like Google, Microsoft etc).
You should have some basic knowledge of C, Java, Git, Bash, HTML etc.(ideally you should be capable of full stack development)
Q.-> I have good GATE score but i want to do my MS from top foreign universities ?
Ans. -> Good. First you have to improve your profile. According to your interest you can join some lab as research assistant under some professor. In this job you can publish papers in A+ conference, learn subject in greater depth and parallelly you can prepare for exams like GRE etc.
It may be possible that whatever you like is not offered by Indian Institute or experts are not available in India in that case you have work little harder to improve your profile.(You can also join some R and D company as intern who is working in the similar area if possible).
And if nothing works then till the time your GATE score card remains valid, admission in M.tech or P.hd could be taken.
I hope provided information will help you in achieving something classic. It is our prime duty to help others because society has given us so much. If there is any mistake in provided information OR you need answer of any other query please notify.
PS: One additional advise it will be good if you can find some life partner in 4th sem.(not before. Do some data analysis till 3rd sem :)) whose frequency matches with yours because it is always good have someone who has some resonance with you and relationship failure chances will be less because you have investigated them till 3rd sem. :)