You need to be more specific. Vulnerable to flooding, erosion, saltwater intrusion or what? People, infrastructure, or ecosystems?  On a global scale, Asia tops all vulnerability lists, with China, India and Bangladesh having most people and materials at risk. Cyclone exposure makes things worse, as does subsidence in deltas resulting from reduced sediment input and pumping of freshwater.

Mauritius?

Interesting! On a global scale, I think Mauritius would count as fairly low risk, because there is relatively little low-lying land. The coral reefs should be able to grow faster than sea-level rise. For the mangroves and other coastal ecosystems, it will depend on sediment input etc. From my brief experience of the island (as an external examiner at the University), I would suggest the major concerns would be the impact on tourist beaches and related infrastructure, and the possibility of increased cyclone damage.

I think all flat coral reefs have high risk from storms. Look at the Kiribati people constantly moving their homes and trying to find a place to cultivate. The Vanuatu typhoon tragedy is a stern warning to all that sea level rise has disastrous consequences.

Have many people switched away from burning fossil fusel to minimize the damage? Not many! Canada, which used to be an example to the world, has achieved a 30 % INCREASE in emissions instead of cutting by 20% (Kyoto). However, the present nightmare government will probably be wiped out in the coming election -solely based on its anti-environment policies.