If you give Mom the funds back then yes, absolutely, you can contact the police to file a report and pursue the daughter. Or, are you trying to get the police involved prior to actually being out the funds?
But, if the daughter is telling the truth, then shirley she still has the $2000 in her account, right?
Tell her to give it back to Mom and you won't have to contact the police.
And definitely make this a teachable moment for the employee who left the card active...