When you go to click on the extras menu and view the trailer so to speak, I have found who plays the song that they play while you go through her house in reverse.

Mozart - Requiem in D Minor

Yes, it's an edited version of Lacrimosa, the eighth part of the Requiem.

Only the first eight bars were written by Mozart himself, the rest was completed by F. X. Sussmayr after Mozart's death.

Here's the lyrics:

Lacrimosa dies illa

Qua resurget ex favilla

Judicandus homo reus.

Dona eis requiem.

Amen.

(Tearful that day,

on which will rise from ashes

guilty man for judgment.

Grant them rest.

Amen.)