Diploma

Are you going to change your branch after completing Diploma. I think you have no interest in mechanical field. It's not mandatory to jump into the same industry. There are wide options available for them. You can analyse your personality and can move into some different career path according to your wish. These some branches B.Tech in Electronics or Electrical (ECE or EEE) - if you love electronics.
You should go with mechanical engineering because today's market is on high demand for mechanical engineers and hence, doing B.Tech after Diploma in mechanical engineering is one of the best options students can go for. Diploma holders get lateral entry in B.Tech through LEEP, which spans over a period of 3 years. After earning graduation degree in mechanical engineering, you will eligible to apply for various private sector and government sector companies.
For admission, you can visit many colleges like SKIT, JECRC or Anand International College of Engineering, Jaipur. According to my view, Anand ICE is flexible in choosing addition courses, faculty, classes, class-timings and opportunities to do startups through incubation facilities at center.