a good percentage in b.com(h) is the basic requirement to get into a good reputed institute for mba.c b.com(h) is the degree which u will get without any doubt bt ca is a risky degree.u never know u will get thru or not.so in my opinion its better to secure one degree without any gap so that u can keep option of mba open for u,as b.com(h) is also an important course and u cannot take it for granted,secure ur b.com(h) degree and u can gv ca exam after that whole heartedly as after giving b.com(h) ur devotion to ca exams wont get divided and u'll b able to devote ur 100% to ca without any tension.and u 'll b hvg b.com(h) degree in ur pocket.
thru my rxperience if one gives ca exam after completing b.com(h) then cracking ca exams becomes much easier and sure shot as both the courses complement each other.
all the very best