Your father seems to be experiencing a phase that is common in nursing home patients. It is often a sign of disturbed metabolism of medications. I have experienced this with some members of my parish and found that medical intervention is invariably helpful. Our local hospital has a Behavioral Health Center which has helped a great deal. It is often necessary for the patient to be hospitalized for a week or so in order for testing to be accomplished quickly and efficiently.
Please alert his doctor to the situation and seek help. It doesn't have to be a family fight or complete meltdown for your mother. I'm sure that her cortisol levels are dangerously high and that her health simply won't hold up under the strain. That's the way we are all made and we can't ignore the consequences!
God bless her for her valiant struggles! Now it is your turn to try to help out!