How to get from Mauritius to Madagascar?
And there is only one option - by air - about 300-400€/person
You can go to Tana or change in Tana to Nusi Be.
I would recommend not considering the "mainland", only Nusi Be and the surrounding areas (islands), otherwise you might wear yourselves out on the road and the impressions will be jumbled, it will be like having been to a marathon.
Moreover, there are good hotels in Nusi, and all the same animals (all possible lemurs, chameleons, and others) - everything is convenient and close, and without any hassle.
Thank you!)