The buses from the airport (N 98) stop on the sea front at the stop called ‘Congrs/Promenade’. Walk back along the sea front and the first street on your right (you need to cross the seafront street) is Rue Meyerbeer and the hostel Meyerbeer is down Rue Meyerbeer about 60 meters from the sea.
From the train station:
Its just a quick straight walk. As you come out of the station, cross over the main road and go towards the right. A bit further along there is a big red brick building which is a post office on the corner of Rue Gounod. Take this street. The Rue Gounod becomes the Rue Meyerbeer after about 5 minutes. The hostel is at 15 Rue Meyerbeer.