thr is quote 'if u put 100% of ur efforts then u get 100% results but if u put 50% efforts then u wont get 50% results' so if u dabble in IAS, CAT and CA chances r u may nt achieve desired results in any of them as they all demand dedicated efforts nd determination. so introspect urself wat kind of life u foresee for urself 5 yrs/10 yrs down d line and then decide..

Firstly bhagat there is no shortcut to success so u can have big change(big salary) only after hard work for which you would need to work. As you work and gain experience the salary would automatically increase according to your hardwork and dedication.
Also to your question whether u shud go for CAT,CA, OR IAS then i guess first you should understand what actually you want. If its only about money then instead of preparing for exams get a job and work harder and the time you would take to complete CA or MBA that extra years of experience would improve your salary as you already possess LLB & CS Degrees which is a great combination with B.Com.