From the airport:
Take the bus 1187 in the direction of Westbahnhof. Go as far as Westbahnhof (Western Train Station) and there you change into the underground line U6 in the direction of Floridsdorf. Get off at the Thaliastrasse stop and walk to the hostel. You can also walk from the train station to the hostel.

From the bus station:
When you arrive at the bus station on the Landstrasser Haupstrasse, take the underground line U3 in the direction of Ottakring and get off at the Westbahnhof stop. Change into the underground line U6 in the direction of Floridsdorf. Get off at the Thaliastrasse stop and walk to the hostel. You can also walk from the train station to the hostel.