1. If your uncle is the sole owner of the property then consent of his wife is not needed
2. If he wants to prohibit his son from entering into the property, he can simply submit a letter to the local police station which has jurisdiction over the property that he apprehends that his son might trespass into his property without his permission and use the same for illegal purposes
3. The above letter will be for record, information and file of the police
4. He can also issue a public notice in 2 local newspapers, one English and another in local regional language, informing the public that he is sole owner of the property and that no one should deal with his son for the same, else such person will face legal action
5. A notice can also be pasted on a conspicuous part of the property stating that it belongs to your uncle and no one should enter the same without express license or permission
6. If the son breaches these restrictions and illegally enters into the property then a police complaint for criminal trespass can be filed against him
7. One more option is to file a civil suit in court and claim injunction relief against his son restricting him from permanently entering into the property