MCA

That depends on the college and whether your Diploma is considered equivalent to class 12th.

Hi,
M.CA. Eligibility. Any graduate who has passed or appearing for the final year degree examination in any discipline (Science, Commerce, Arts, Engineering or any approved University) is eligible to apply. Candidates must have mathematics as a subject in their 10+2 course or any one year of graduation.

https://www.shiksha.com/it-software/course/master-of-computer-application-gujarat-university-navrangpura-ahmedabad-120871
Check out this link, and if the university mentions no specific UG requirements, then you are eligible

VSKU
RYMEC
These are the generally recommended ones.

Hi,
The TANCET Syllabus for MBA is different from the MCA syllabus and the TANCET Exam structure for MBA exam also has different components.
MBA stands for Master of Business Administration and MCA stands for Master of Computer Applications. The duration of MBA course is of 2 years and of MCA course is 3 years. One thing I suggest you is, give much importance to get the job which you are interested rather than to get the job where you will be paid high.
Good luck.

https://christuniversity.in/sciences/computer-science/master-of-computer-applications-(mca)
Refer this link.

Yes, you can, provided you qualify all other eligibility requirements laid out by the college.

MCA is for a period of 2 years.

Since you haven't got a job in 3 years, I would suggest you change fields and opt for something that interests you and complements your skillset.

Most of the colleges in Gujarat accepts CMAT for MCA admission. There are few more colleges, but you would have to check individually.