Welcome to APUG.
I'm not sure, but I'd guess that the Brownie uses what is called 620 film. The more knowledgeable here can advise better.
But if so, while that film size is not "in production" per se, there are some sources to obtain adapted stuff that will work in your Mom's camera.
My Dad recently unearthed a similarly old Kodak camera and I was able to find some "adapted" film to fit it and shoot him ( ) for Father's Day!
I hope the Brownie is just a seed that will grow into a bigger tree of interest in film photography - but, anyway, welcome!