Hello Welcome here. I can understand your concerns for your father. Mood disorder in the form of irritability and anxiety is fairly common in old age. But you have to keep check on his blood pressure as high blood pressure can cause these symptoms also. Drugs like clonazepam or alprazolam (prescription drugs) when given in low doses can help to control his behaviour. Never try to argue with him for his acts. Take care that he might not harm himself or others out of his irritability. Hope this helps. Thanks.