Sir my mother's estimated creatinine clearance rate is 65.85 ml/min .....what is the interpretation??

There are 2 tests to check the function of your kidneys. One is a blood test called serum Creatinine and the other is called creatinine clearance(often calculated from the blood creatinine level). Normal creatinine level is about 1-1.5mmg and the clearance is more than 60/minute. Based on this, your mother's kidneys are functioning normally at this time.

Isolated lab values cannot be interpreted out of clinical context and dynamics (without comparison with previous values). From a normal/ abnormal standpoint such an eGFR appears borderline normal.

All laboratory results need to be interpreted in the clinical context and the doctor who ordered the tests is usually in the best position to do that. Talk to the doctor who ordered the tests. Having said that, her kidney function is sub-normal and you should consult a nephrologist to avoid further deterioration. Wish you good health!