B1 B2 Mistake - Apply for B2 Parents Visa Dropbox - How to fix ? Renewal?

My mom is 74. Her visitor visa B1/B2 expired in Aug-2020. I filled ds160 for her. We paid fees as well. We did not receive confirmation email about MVR fees receipt. So inquired at ustraveldocs email address and they confirmed they got the fees and attached to the case and asked us to schedule interview online. No indication whether we can use Dropbox method. Are we eligible for drop box? How do we make sure we can get drop box method for my mom? Her old visa was from 2010-2020. She got a new passport in 2017. Her old visa was B1/B2. The form we filled this time we applied for B2 visa as she can’t be doing business B1 allows. How do I rectify my mistakes? Thank You.

Well, Not sure, if the previous mistake can be rectified now as it was done 10 years ago.
I am not sure, if you would be eligible for dropbox as B1 and B2 are seperate Categories altogether. Write to consulate on the honest mistake and give it a try, if they allow to file for B2.
Also, do update how it goes here for everyone benefit.

Hello Kumar - thanks for reply. Prior visa was broader category B1/B2. New application is B2 which is a subset. Is that a mistake we chose B2 instead of B1/B2? Do you recommend we write to consulate and ask them to modify our visa application category from B2 to more generic B1/B2 so that we can be eligible for dropbox?