I would highly recommend your aunt see a Registered Dietitian who can read her medical record and instruct her on the best nutrition therapy for her health. Your local hospital or clinic is a good place to start. Call and ask to talk to a dietitian. I would need the same info to determine if she needs to restrict protein, potassium and/or phosphorus.
Since protein is often restricted along with potassium and sometimes fluid in a renal nutrition therapy, I would highly recommend your aunt make an appointment to see a dietitian. She needs to learn the best sources for the nutrients that may need to be restricted as she recovers to health.