Her son controls her

Our problem concerns my husband’s mother. Her youngest son is living with her and he does not do anything for himself and does not work, even though he is in excellent health. He is forty years old and he controls his mother. She does whatever he dictates to her to do. My husband has been spending on them for 35 years. This son of hers incites her against everyone and dictates who she may be pleased with, according to his interests. My husband works abroad and I cannot visit her because he does not want me there. She threw me and my children out and she is foul-mouthed and does not fear Allaah. They visited me when my husband was here and she and her son attacked me and tried to hit me, and they managed to hurt me. My husband and my son who is a university student defended me. The outcome was that they hurt us, then she went out in the street where she started to scream. She went to the police, and she made a complaint against everyone and demanded that my daughters and I be detained in a place that was not befitting for us. Even the police officer told her that we are respectable. My husband and son were detained and he was supposed to sit exams. His studies have been delayed for a year because of this. After the trial, we paid her the required maintenance; before that my husband used to give her more, but my husband cannot visit her, and the reason for that is that she had her daughter’s husband and his son jailed when they visited her. The problem is that whoever visits her, her son locks the door and calls the police; even her own daughters have the same problem. When her oldest son visited her, he could not enter and her youngest son stopped him and took the money and gifts (that he had brought) and told him, “Your mother will pray to Allaah against you.” 
I do not know what to do or say. I complain to Allaah of my worries. I would like to visit her and honour her, but they is no way I can do that because they fabricate lies against everyone who visits them. What should I do, knowing that I am a grandmother and I fear Allaah. What can I do and what is the shar’i ruling on this?.