Since you have done Diploma in Computer - science, you can go ahead for the job in your related field. In fact, there are numerous short term certifications such as Java, Oracle, Linux, Software testing etc and these certification will certainly enhance your job employability in the IT field. Once you enter into your job, start preparing for AMIE since this course is at par with the syllabus being followed in BE computer - science. Moreover, this course can be persued in your convenient time and in either of the sections - section A or section B, papers can be cleared part wise without hampering your normal job- activities. Though the clearance of the course is time - consuming but with your own passion and interest, preparation can be shortened by appearing in both the sessions - May and November in a calendar year.
With your accumulated work - experience and aquistion of AMIE qualification, your prospects in the job will widen.
You can go in for BBA or MBA but not at this stage. It would be better to have a job first and then you may persue BBA through the distance mode and later MBA can be persued with the continuation of your job.