Although most frequent flyer programs group Mauritius with Africa to determine it’s zone, there are far fewer options because not many airlines fly there.
South African Airways is the only Star Alliance member to serve Mauritius so you will have to get to JNB, then connect to Mauritius. Availability on this route isn’t the best and sometimes only available in business class so if you can only afford an economy ticket this won’t work for you.
Assuming you can find availability, one way (double for RT) awards would cost:
NORTH AMERICA – MAURITIUS 40,000 Y 80,000 J
EUROPE – MAURITIUS 30,000 Y 55,000 J
AUSTRALIA – MAURITIUS 50,000 Y 75,000 J
Given the distances involved, it is much better to combine Mauritius with South Africa and have a better chance of finding those elusive seats!
The only OneWorld carrier serving Mauritius is British Airways so the best programs to look at are American AAdvantage for long-haul segments and British Airways Avios for short hops from JNB-MRU.
Beware of transiting LHR enroute to Mauritius as the airport taxes can be extremely high. Try to route on QR via DOH or EY via AUH to JNB, then pick up the JNB-MRU on BA. Assuming you can find availability, one way (double for RT) awards would cost:
NORTH AMERICA – MAURITIUS 37,500 Y 62,500 J
EUROPE – MAURITIUS 30,000 Y 37,500 J
AUSTRALIA – MAURITIUS 37,500 Y 50,000 J
American currently offers the best deals on mileage awards to Africa but these rates are unlikely to hold once the merger with US Airways is completed so if Mauritius/Africa is on your bucket list, this is a good time to book your trip!
Air France is the only SkyTeam member serving Mauritius but you can use Delta (if anyone is still a member of Delta) to book these awards. If you are using credit card points or transferring from SPG, then Flying Blue is your best bet. All SkyTeam members charge YQ fuel surcharge on these tickets so you are better off using United or American for long haul awards. Here’s a couple examples for a North American award and a European award. Flying Blue won’t let you route from Australia via Europe to Mauritius.
Air Mauritius dominates the market. Here is a list of their destinations from MRU.
They are a partner of Air France Flying Blue but they are not a member of SkyTeam. If you want to use Flying Blue miles to book Air Mauritius you will have to call in. I tried on the MRU-TNR (Antananarivo) route but the fuel surcharges were so high it would have been a total waste of SPG points which can be better utilized elsewhere. If you are booking a cash ticket, then Air Mauritius does have a lot of options, keep an eye on their website for specials.