Your mother’s symptoms are consistent with neurogenic claudication caused by spinal stenosis. To make that understandable, this condition causes a significantly narrowed spinal canal. The spinal canal normally narrows in diameter by 30% with standing in every human on the face of this earth. We never notice it because there is capacious room in the canal with most individuals and 30% is never normally a problem.
However, with age, some individuals develop a narrowed canal. this occurs because of bone spur, a vertebral shift (degenerative spondylolysthesis), hypertrophy of the ligamentum flavum or a disc herniation (see website descriptions and pictures of this).
Treatment for this condition can be injections and physical therapy. Patients on anticoagulants, with proper care, can be temporarily taken off, given an injection and then placed back on. That is unless there is a significant danger posed to the patient by being off anticoagulation for 24 hours.
This condition can be treated surgically. A decompression laminotomy can be performed or an interspinous device can be implanted. There are times a fusion may be necessary.