Broadly there are five specialization in MBA, namely marketing, finance, HR, systems and operation. Out of these systems and operation are normally engineer's cup of tea. You can opt for marketing,HR and finance. Normally, you have to choose your electives at the end of first year only. By that time you will cover basics of all specialization. You can decide topics upon your interest and aptitude.  I know many people who joined MBA with the intention to specialize in particular branch and later they changed their decision when they deeply understood about each specializations. Now you should focus on getting admission to a good institute.