Visitor Visa - B2

Hi,
I had applied for the visa first time in around 2014 with my mother, My younger brother is in US and he was sponsoring us. But I was in between jobs, so my visa was rejected. Luckily my mother got visa. Now My brother wished that my mother could come for vacation to his place in US. As she cannot travel alone(she cannot speak in English), so I applied for visa and I got an appointment on 24th of June. On the query of purpose of visit, I said the same thing, that my mother wish to take vacation with my brother, she cannot travel alone so I'll be accompanying her, travel some nearby places and return in couple of weeks. My brother Is capable and is sponsoring all the expenses of both stay and travel for the vacation. I am working in a multinational company with a senior position for more than 2 yrs, also with an income that I can bear my travelling expenses. I am married just a year ago. But my visa was rejected again.

So what went wrong ? I was all prepared with all the information available on the internet. Twice my money was wasted.