What should we do regarding the money we took from our father in the name of the maid, without her knowledge or our father's, knowing that she has traveled and we cannot contact her?

If the father paid the maid all her dues and did not account against her the money you took in her name, then the money belongs to him and must be returned to him. However, if the father did account the money against her and deducted it from her dues, then it must be delivered to her if she can be found through recruitment offices. If it is not possible to reach her, then the money should be given as charity on her behalf. You must seek forgiveness and repent for lying and betrayal.