Based on the information, your mother probably suffered from a rare complication of surgical procedure of nephrectomy, namely “incisional hernia”. It involves protrusion of tissue, fat or even an organ through the inner surface of abdominal wall weakened by the surgical scar at the site of initial incision from the surgery. It can occur months or even years after the surgery. Wearing a belt or a brief/elastic band can help reduce the protrusion thereby minimizing the symptoms of discomfort though it can never cure it. My advice would be to follow up with the surgeon who would probably recommend the surgical correction of the hernia as a definitive treatment based on the severity of the problem. In the meantime, she would need to avoid lifting heavy objects and continue wearing the abdominal belt.