Do we appeal the ESA decision or apply for PIP?

Hi,
I have an enquiry, I am eager for answer from anyone, my mother was receiving ESA for one year , then they arranged her face to face interview for health assessment, then they sent her letter after interview said her benefit will be stopped within few days as she is fit for work  and they stopped it , my mother very sick and in pain , I don’t understand how they say she’s fit to work , she barely can walk and move.
after few days later PIP sent letter says thank for your application and soon we will send you form to fill (we were confused as we never applied for PIP).  Anyway we filled the form and sent it back then they sent a letter for face to face interview .
we are confused because we want to appeal ESA decision but PIP sent face to face interview.
what we do now I need your advice, we feel we are lost , do we appeal the ESA decision or we forget about ESA and go ahead with PIP ?
staying with ESA better or PIP
i appreciate any answer from anyone