Veterans

Your mother is definitely eligible for the Aid and Attendance pension benefit (https://www.veteransaidbenefit.org/aid_and_attendance_pension_benefit.htm). You do need to go through a fairly detailed application process than includes getting doctor's signatures on her need for custodial care. You will also need to document all her income and expenses and organize it in a way that a potential reviewer can wade through all the paperwork (table of contents or index).

There are some people who prepare these VA applications professionally for survivors or veterans. But, you can do it yourself with a bit of due diligence and careful preparation. I did it for my mother who was in assisted living facility and later moved to a nursing home. It was incredibly helpful and paid on par what she received from the Social Security Administration.