There is a form to be filled out and signed by a physician which the patient then submitts to the motor vehicle administration to get a handicapped placard for use in her own or anyone's car in which she is traveling. It is not just for wheelchair-bound persons. My mother's cardiologist filled out her form. The numbers did not carry over, but below are the reasons for which your mother could get a placard. Show them to her doctor or get one of her specialists to fill out the form.
Conditions for Special Parking Placards or Registration Plates
Has lung disease to such an extent that forced (respiratory) expiratory volume for one second, when measured by spirometry, is less than one liter, or arterial oxygen tension (pO2) is less than 60 mm/hg on room air at rest.
Has cardiovascular disease limitations classified in severity as Class III or Class IV according to the standards set by the American Heart Association.
Is unable to walk 200 feet without stopping to rest.
Is unable to walk without the use of, or assistance from, a brace, cane, crutch, another person, prosthetic device, or other assistance device.
Requires a wheelchair for mobility.
Has lost an arm, hand, foot, or leg. See Note (D) Certification Under Maryland Law.
Has lost the use of an arm, hand, foot, or leg.
Has a permanent disability that adversely impacts the ambulatory ability of the applicant and which is so severe that the person would endure a hardship or be subject to a risk or injury if the privileges accorded a person from whom a vehicle is specially registered were denied.
Has a permanent impairment of both eyes so that: 1) The central vision acuity is 20/200 or less in the better eye, with corrective glasses, or 2) There is a field defect in which the peripheral field has contracted to such an extent that the widest diameter of visual field subtends an angular distance no greater than 20 degrees in the better eye. See Note (C) Certification Under Maryland Law.
Temporary Placard (red)
Disability is not permanent but would substantially impair the persons mobility or limit or impair the persons ability to walk for at least three weeks, and is so severe that the person would endure a hardship or be subject to risk of injury if the Temporary Placard were denied.