Is the custodian obligated to transport the children to and from school and to cover their transportation expenses, given that the father used to cover their school bus transportation, and that this conflicts with her work and study hours?

Educational expenses are not included in the obligatory financial support (nafaqa) from the father. Therefore, he is not obligated to transport the children to school, as this is a consequence of their schooling. As for the nanny's wages, the majority of scholars hold that they are obligatory upon the father, while the Malikis dissented on this point. If the father commits to paying the obligatory nanny's wages, and also undertakes the non-obligatory educational expenses, then it is fair for the mother to contribute by transporting the children to their school, especially if it is close to her residence.