In Mauritius you can exchange all your money. Believe us, it is not difficult. The best way is to find a bank or in your hotel. Banks work from 9.15 to 15.00-15.30 on weekdays and from 9.15 to 11.15 on Saturdays.
Moreover, you should be aware that rupee exchange is possible only at the airport. So, you can change local money only in case of departure from the airport.