Giving a walker to a senior who's docs don't know about it. Any advice?

My mother has balance and mobility issues. She is only 68. She wants dad to get her a walker at a yard sale. I am against this as if she needs a walker her docs should know and also be prescribing PT and keeping an eye on balance and mobility. My dad is afraid they will revoke her licence if she has a walker perception so he is on the fence. Ideas or thoughts? Thank you!!