Documents for legal guardian proof for senior citizen's passport renewal

Thank you for all you do. I have clarified most of my questions through your site. I am renewing my mother’s passport. I have changed her address to US address as she is a permanent resident. In the last page of the passport where I have to fill out parent/legal guardian, I have put my name. What documents do I have to submit as proof of legal guardian? Does it have to be notarized? (what ever they are)

Check with CKGS as to what documents are required.