Woke up to one of my girls dead

This was Melly (named after a formel which is a female hawk because she looked like a hawk.)

I woke up this morning to check on the girls and Melly was dead out of nowhere. She was 11 months old, laid a perfect blue egg Wednesday for us, and today shes gone. We're pretty upset about it but I'm most concerned to why this happened. We have 7 others in our flock now and all seem happy and healthy just as Melly did yesterday.

Any ideas?