All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
We ask Allaah to bless your daughter with good health and to reward you for caring for her and for being keen to know the religious rulings.
You have to know that one of the rules in Islam is to facilitate worship if one is unable to perform a specific act and he will not be held accountable for it. Allaah says (which means): {And has not laid upon you in religion any hardship.}[Quran 22:78]. Allaah says (which means): {Allaah burdens not a person beyond his scope.}[Quran 2:286]. So whenever there is a hardship [in performing an act of worship] the easiest permissible way in Islamic Law is opted for, in order to minimise the difficulty on the person.
As regards her wearing Hijab, it should cover her entire body including her face and hands in the presence of marriageable men according to the most preponderant opinion. You could fix the veil on her head and attach the face cover using pins or anything else which could be used for doing so. If this cannot be done, then she should fear Allaah and adhere to his commandments as much as she can.
With regard to ablution, if she cannot perform it on her own, and this is what we understood from the question, then another person could help her perform ablution, by washing her face and hands but it is not sufficient to wipe them. Allaah says (which means): {Wash your faces and your hands (forearms) up to the elbows.}[Quran 5:6].
Finally, it should be noted that it is not permissible for the female servant, if she is a non-Muslim, to help her in performing ablution; as it is not certain that she will help her to perform ablution in a proper way.
Allaah knows best.