If I'm still married and me and my husband had a verbal agreement to keep the kids while I go find work in another state? His mother filed the charges its only been 3 months?

What exactly did your mother-in-law file? Because generally you can't "file for abandonment". You can use abandonment as grounds for something else, so what did she file? And why is she filing. If you went looking for work and left your husband with the children, then he has to file, she has no standing to file anything.

I don't see anything that supports using abandonment as grounds for anything based on what you have told us. Also ANY question on law needs to include your general locale as laws vary by area.

Yes, mother in law has no legal standing if you and husband are still married, and your husband was keeping the kids.

So what does his mother have to do with this at all. Did he dump the kids off with her ?
Or did you and him both leave the state and she have the kids ?

But you don't charge someone with it, you use it as a reason to file a civil motion to change custody.

Or, if the children are left without adult supervision of any kind, that would constitute a different form of abandonment; one for which the mother-in-law could report the parents to the police.