Hi,
After completion of diploma course a student can take direct admission in btech 2nd year through lateral entry .
They can also apply for various government and private firms. some of the job roles they can choose are-

IT support engineer
Technician
Software developer
Network engineer
Database administrator
You can also work in armed forces in fields like signal department , maintenance of radar, on board computers, etc.
Also in government PSUs like Hindustan aeronautical limited , bharat electronics limited, Indian telephone industries and various others .
Hope it helps...