Hello Gowtham,
I am very happy that you have asked this question so early, because you pretty much time to decide.
So look first thing that you should remember before choosing any branch is the interest. For example , if your having interest in physics and maths then you should go for mechanical engineering as it is a evergreen branch. If you don't like physics but do have interest in programimg then you should choose CSE or IT.
I telling you this because whatever the high scope of branch you are opting, if you don't have passion to learn about it,then you are going to be a bad engineer. In the end you will always regret it. So first thing first choose what you like.
Now coming to scope of different branches Mechanical engineering , as I said scope is always high. But remember company only selects the best. CSE and IT is also in boom, as you know our life is completely bounded by gadzets, so demand of CASE and IT is also increasing.similar for electrical and electronics.
But one branch which is going to get a increasing boom is , I feel robotics and mechatronics.
Robotic and automation sector is currently in infant stage but in future it's going to do a lot of impact.