How would you explain why you got an MBA after completion of your BE in Information Technology?

You should always answer interview questions honestly. Of course, that doesn't mean that you shouldn't carefully think about your answers in advance, as you are doing now. It is important that you clearly understand your own life story. Work in out in your head, on paper, and out loud to friends or family. Explain why you have made the various important choices in your life. Summarize it and replay it, so it becomes a coherent, logical path. In your case, this means figuring out why you decided to get an MBA. Think carefully, and develop your story. Make sure it makes perfect sense to you, then test it on others, then you'll be ready for anything an interview can ask.