Is preventing the father from traveling for Hajj due to a forged visa considered ihsar (hindrance), and is he obligated to offer a hady (sacrifice) even though he did not slaughter it at the place of ihsar, and does this absolve him of the obligation of Hajj?

If your father did not enter into ihram, then he is not obligated to proceed with the rituals. However, if he entered into ihram and was then prevented from completing the rituals, he must exit ihram by offering a sacrifice (hady). If he is unable to do so, then he must fast for ten days, and the obligatory Hajj remains an unfulfilled duty upon him. If, when entering into ihram, he stipulated, "My place of exiting ihram is where I am detained," then he exits ihram and nothing is incumbent upon him, and the Hajj of Islam remains an unfulfilled duty upon him.