CA

There is no age limit for education and you are just 24. CA is a 3 year course. You can opt for it and complete it in 3 years with hard work. Even if you take some time and complete it by the age of 30, there is no problem. Keep that excitement and go ahead.

You can do both because it is always better to have one option in your hand to be on the safer side.

A B.Com graduate can apply for jobs in any organization for an entry level opening in accounts department. The entry level job would be of book keeping, maintaining books of accounts, making JV entries, etc. A pure finance role may not be available for a B.Com graduate. With experience in accounts, one can explore opportunity internally/externally into the pure finance domain.

You can do MBA through CAT, MAT, XAT, CMAT, ATMA, etc. You need to score as much as possible. You will easily get decent b-school, if you score well in any of the above mentioned entrance exam.

Hi,
You can go for C.A. after B.com.
There are 3 stages in C.A.:
CPT
IPCC
Final
Common Proficiency Test (C.P.T.), which is required after 12th is not needed after you graduate in B.com.
Only thing you need is that you have to undergo Articleship under a C.A. then only after that you will be eligible to write IPCC exam
After successfully passing the exam you have to continue the articleship and then you can appear for the final exam.
If you join any of the C.A. coaching institute then they will provide details and assistance regarding Articleship and other valuable information.

There shouldn't be any exam phobia. Regular problems practices and continuously work on basic concepts will help you to remove the exam phobia. Try and solve mock papers of CA with required time limit and work on speed while solving mock papers.