What is the ruling on the actions of a father addicted to hashish who conceals his money from his wife, complains about her shortcomings in intimacy, and hints at marrying another woman after 36 years of marriage?

Your father has transgressed against Islamic law in his ill-treatment of your mother, his stinginess towards you despite his large salary, and his consumption of hashish. You should remind him of Allah gently and kindly. If he does not respond, seek help from people of knowledge and goodness, provided no harm results. Otherwise, limit yourself to prayer. As for his request for intercourse, it is his legitimate right at any time, as long as there is no Shar'i impediment, and your mother has no right to refuse. And his talk about marrying a second wife is permissible for him in Sharia (definition), and there is no need to be angry about it.