Your doctors have not been patient enough to educate you on the anatomy of the spinal nerves First, the spinal cord terminates (ends) behind the body of the first lumbar vertebra (L1). Their reasoning that surgery “may lead to complete body failure due to some reasons relating to spinal cord’ when your mother’s problem is at L3-5 (no spinal cord) is obviously not accurate.
You note your mother has “severe back pain” but that does not differentiate the symptoms enough to describe what these findings on MRI can cause. See the section “how to describe symptoms” to fully convey what your mothers symptoms could be. Also, you can look at “herniated disc”, “spinal stenosis”, “lateral recess stenosis”, “foraminal stenosis” and possibly “degenerative spondylolisthesis” under the lumbar spine conditions section as these all are potential conditions you mother has.