Is my sister’s shunning of her husband’s father, who does not pray and does not perform ghusl, out of fear of his bad smell, considered an act of disobedience?

The sister erred in asking her husband not to host his father. The husband should advise his father, who insists on abandoning prayer, with gentleness and by choosing the appropriate time and method, reminding him of the gravity of abandoning prayer and the torment of the grave. The wife should assist her husband in honoring his father and repent to Allah for her role in helping him sever ties with his father. She should also endure any harm that may come to her from her husband's father.