Is it permissible for the mother to cover up for her daughter and not inform the father of what happened to her, or must she inform him?

The sister must conceal her sin and not inform anyone about it. The mother must also conceal her daughter's sin and not inform the father or anyone else, while protecting her daughter from bad company and keeping her away from temptations. The sister must achieve sincere repentance and increase in good deeds and effacing good actions.