No, there is not even one college that made it compulsory to take the whole PCMB. Either you can take PCB or PCM or else you also can take the whole PCMB. It depends on your choice whatever you like you can choose it.

If you want to make a career in the bio you can take PCB

If you want to make a career in engineering or maths you can take PCM

Or if you are not sure about your career you can take PCMB.