Is a woman suffering from multiple sclerosis, who has become irritable, quick to anger, and verbally abusive towards her parents due to her illness, considered sinful, and will her Lord punish her for that?

If a person's anger reaches a point where he does not comprehend what he is saying or doing, then he is not held accountable for what emanates from him. However, if the anger does not obscure his comprehension, then he is held accountable for the words and actions that emanate from him, and the sin increases if it is directed towards parents.

Raising one's voice at parents in extreme anger is considered disobedience (uquq), unless the person is not in control of himself, in which case he must seek their forgiveness and apologize to them.

The whisperings of anger upon seeing people carry no sin as long as they do not translate into words or actions.

To curb anger, a person must discipline himself to submit to reason, and remember that Allah's anger towards him is greater than his own anger, and that His grace is greater.