A song you sing to protect your child while they sleep is called a lullaby.
The readings for this word are all kun'yomi readings. You haven't learned this reading for 守 yet, so here's a mnemonic to help you:
When you finish singing a lullaby to your child they always ask for more (もり). It doesn't matter how many you sing, they always want at least one more before they will fall asleep.
Kristen's lullaby has reached the professional level.
What's the most popular lullaby in America?
It's a lullaby that was sung for me when I was little.