H4 visa or B1/B2

My husband is in USA on H1B since past three months. I am planing to travel to USA for a month in Oct. I am however not sure if H4 visa is the right choice or shall I Apply for B1/B2

I understand H4 visa is valid for the duration of whcih H1B is valid. How Long is B1/B2 valid and what is the ideal visa for my situation as I only plan to stay there for a month and come back to India.

Regards

Poonam

H4 is the right visa for you.B1/ B2 can be rejected