You might assume it's the director trying to throw a bone to his nephew's music career, but it's actually a reference to the 1978 Halloween. That's the same song Laurie is singing while being stalked by Michael's menacing shoulder blade.
Compass International Pictures
And here's the crazy thing: It's not even a real song. On the very first day of shooting, director John Carpenter told Jamie Lee Curtis to "just make up a song" to sing to herself. Curtis improvised what came to be known as "Close To Me." For the 2018 Halloween, director David Gordon Green hired a band to write and record a full version of the song, as if it were always a hit tune in the Halloween-verse.
It's a fun nod to the first movie -- and incidentally, way cheaper than a real song that exists outside of Jamie Lee Curtis' brain.