Bus:
Either take a bus from Landeck in Austria or a its a 20min from Martina in Switzerland
Train:
Nearest station is Landeck, there is a bus available to Nauders. Or train to Tarasp Stabiliment da Cura in Switzerland, then bus to Martina on the border, and another to Nauders
Driving:
Easy drive from Switzerland over the pass or via Innsbruck/Landeck in Austria
Flying:
Nearest airports Innsbruck, Bozen and Zürich