Can I do MBA after completing Diploma in electrical engineering?

No, since, MBA is a post graduate programme. You need to be a graduate to pursue it.

No, you can't do MBA after completing your Diploma, because the criteria to do MBA, is that a student have to complete their graduation by 50% aggregate. So, I suggest you to do B.Tech in electrical engineering. Good luck, go ahead.

No. You need to be an undergraduate. You need to score above 50% in UG.

The eligible criteria for doing MBA is a candidate who has completed his graduation degree with minimum 50% marks in degree from any recognised university. So Diploma after 12th is not sufficient to join MBA. MBA is a post graduate degree. So you need to first do your graduation degree for doing MBA