Can apple cider vinegar kill bed bugs?

yea

Nope. But it can make your bed smell like Italian dressing.

Fly spray

No.

I don't think so
https://www.epa.gov/bedbugs/do-it-yourself-bed-bug-control
https://www.google.com/search?q=bed+bug+apple+cider+vinegar&ie=utf-8&oe=utf-8

No, but food grade diatomaceous earth will kill them (along with other insects). The powder is applied along the baseboards of your room using a duster. Food grade diatomaceous earth is non-poisonous to animals and humans and is fed to animals to rid them of parasites.