Final answer:
The name of the piece played by Quaver as part of the final song is not specified in the given texts.
Step-by-step explanation:
The piece played by Quaver as part of the final song was not specified in the provided context. In the first context, a piano was playing songs from various musicals such as 'Chin-Chin' and 'The Count of Luxemburg', but the specific piece by Schumann is not mentioned.
In the second context, Nora asks Helmer to play for her while she dances, but the name of the piece being played is not given.
Based on the information provided, we cannot determine the name of the piece by Schumann that Quaver played as part of the final song.