In the book Night, by Elie Wiesel, there was a friend of Elie's that played music while everyone was dying in the snow, who was the friend?

You are correct
that it was Juliek, a tiny
young Polish boy--who recognized that he would not survive the death

march--begins to play Beethoven on the violin.  It is a marked contrast to the situation
they
are in, and to the main character/author; this makes it all the more
beautiful.

It is a very short section of the book, which
is cut off abruptly when Elie awakens to
find young Juliek dead, his violin
smashed to pieces.  It is perfect symbolism of the
hopelessness of their
situation, and Juliek had accepted this hopelessness, deciding to exit the

world in the most beautiful way that he could.