Is it permissible for the wife to go against her husband's wish regarding who changes the wound dressing, and for her father to substitute a nurse for that task, despite the husband's objection and his desire for the nurse to be the one to do it?

A woman must seek out a female to treat her wound, whether her husband instructs her to do so or not. It is impermissible for a man to treat a wound in the awrah mughallazah (severe nakedness) as long as it is possible for a woman to do so. Looking at and touching for treatment is permissible out of necessity, provided there is no healer of the same gender available. She must repent to Allah Almighty.