Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.

As to what follows:

In response to your question, we say, and with Allah Almighty lies all success:

It is obligatory to remove what is on the hands preventing water from reaching the skin. As for the head, then the matter is simple: if she covered her head with henna, then she has to wipe over the bag or cloth over her head, or wipe over the henna itself (in the absence of any cap). As for whatever is present on the hands, then it must be removed.

As for the one who did it many times and does not know how many times, and also did it out of ignorance, then there is nothing due on her. Neither does she have to make up her prayers, nor give anything in recompense, nor is anything due on her; only that she be aware of this matter in the future (so as not to repeat her mistake).

And Allah knows best.