My daughter moved in to help to take care of my wife. All expenses are on me. Am I her employer?

I would speak with a CPA that understands how that works in your specific situation.

Maybe get a NELA certified elder law attorney that can help you set all of this up for the best tax advantage for all. As well as ensuring that you have all the proper documents so you can do what is needed and God forbid, if something happens to you, your daughter will have the authority to do what you desire.