marcyblue7, welcome to the forum. So sorry your Mom is having all those health issues at only 68 years old, that must be so difficult. I see from your profile, that your Mom's husband is there to help her, too.
As for fixing up the house for her safety, check your County Council on Aging, or whatever it is called in your area, to see what places offer such help.
Those services have long wait lists: veterans housing, habitat etc. You can call your local social services, but not all locations have offerings. If safety is immediate, then moving may be the next step.
Perhaps contact a Boy Scout troop to see if they'd be willing to build the ramp if you provide the materials.
As for fixing up the house for her safety, check your County Council on Aging, or whatever it is called in your area, to see what places offer such help.