Super Top-up / 2nd Health Insurance for Mom

My mom (60) and dad (65) have a joint health insurance policy with Niva Bupa ReAssure, active for over five years, with coverage of 10L. About nine months ago (May 2025), my mom had to undergo an aortic valve replacement surgery costing around 15L. Niva Bupa covered 10L, and we paid the remaining 5L from our savings. That’s when I realized the need for higher coverage. I decided to get a second health insurance policy for both of them with better benefits. I managed to get one for my dad, but couldn’t secure one for my mom due to her recent surgery. Major insurers like HDFC, TATA, and ICICI have rejected her application. Should I look into Public General Insurance instead? Do they provide cashless facilities? Or would a Super Top-up be a better option? Please suggest