Go to a hardware store now.
"If you can't annoy somebody with what you write, I think there's little point in writing."-- Kingsley Amis, British novelist, 1971 t .
This is the most dreadful thing I've read all day, and I have read a lot of dreadful things today. That poor family! I cannot imagine the suffering they must be enduring right now.
I hope that someone benefits from reading your post. We always have working smoke detectors (tested monthly and batteries replaced twice a year), as well as CO detectors, another thing I urge people to get, even if they're not required by law in their area.
I am so sorry for your friend's loss. How tragic, and the fact that it could have been prevented is heartbreaking.