The currency used in Mauritius is called the Mauritian Rupee and the currency code is MUR. The exchange rate from USD to MUR is 1 USD = 39.85 MUR and from Indian currency is 1 INR = 0.53 MUR. The best place to exchange your currency would be upon arrival at the airport as they have the best exchange rates.
However, you could also get your currency exchange at foreign exchange booths or ATM’s found everywhere on the island, these have a better exchange rate than hotels and banks. Although some places do accept foreign currency, locals always prefer to be paid in the local rupee and keep in mind that in case you pay with a foreign currency, your change will always be returned in the local currency and you might lose a little money that way.