J.K.
My kids go through these weird changes when their dad is deployed too. Do you get to talk with your husband at all? Sometimes kids can feel something we can't. My husband was deployed over the summer and one day my 3 year old was constantly praying for daddy to be safe. Her prayers are usually thank you for..... never asking for anything. Once talking with him a few days later I found out that very day the base he was stationed at was hit and many died and was injured. Not to scare you but to maybe help you understand her some.
Was she prepared ahead of time that he would be leaving? Is this his first time gone that she really knows he is gone? All these things effect the way they deal with stress.
My youngest also went from being totally potty trained to back in pull ups the first time her dad was gone. So also is just stress they don't know how to express it and it comes out. The good new is right after dad was home she was fully potty trained again. As Danielle said my girls also had a stuffed animal that dad got for them and we sprayed it with his cologne. I let the kids wear a one of the set of his dog tags always to help feel close to him. We would pick out a star and tell daddy what it looked like so he could see it too, etc.
I'm sorry you are going through this it is very tough of kids and mom when daddy is deployed but start counting down to when daddy will be home (although if it was anything like when my husband was deployed the countdown was a wide timeframe since we didn't know exactly when until the day before he was home). Have her help you plan a party or special trip you all will take together when dad gets home. This will help her see the light at the end of the tunnel. Also you can talk with your family readiness coordinater they may have some advise or know a professional to talk to that can help you help her.
God bless you and Thank you for supporting your husband who is serving our country. Hope this helps :)