Bangalore

DY patil college of engineering is best college with high ranking

Bangalore University

Manish, after completing diploma in Mechanical you can get admission in 2nd year.of B.Tech that we refer to as lateral entry. As first year syllabus for all branches is same, so you can take admission in any branch of your choice.
You have to appear for Lateral Entry Engineering Test (LEET) for admission in 2nd year.of B.Tech. You must have min.of 60% marks in diploma to appear for LEET.
If you have not given LEET, then opt for good private universities like LPU, MIT, IIIT, DBU, etc. They offer world class environment to students along with good placements. Some even offer good scholarships to students. Check their websites.
Good luck.

cut offs are out u can check on their websites but the date of registration for counselling is gone but no tension if you have already registered

Try for RV college of engineering.

All the Central Universities are doing top class job in Humanities. The fact is well -established. For example, consider the reputation of JNU. But, we have to do our bit. It is in our hands. So, you prepare well.