Me neither merry Christmas to you
The instrument described is a clavichord.
Although not very popular nowadays, it was important between the 15th and the 19th century. In popular music, variations of it can be found in songs by artists such as Stevie Wonder and Bjork, but they mostly used the electric version of the instrument.
Subject view because if you don’t know ur subject how would you know ur content composition
Gustav Mahler would be my answer. Strauss was also composing during the late 19th and early 20th but Mahler created more of a fusion between the two.