Is it permissible for a daughter to shake hands with and kiss the head of an elderly shaykh who is the father of her husband?

Question:
He says: I am a man in my seventies. I have had friends since childhood, and I still keep in touch with them, check on their well-being, and enter their homes, and they do the same. They have sons who are like my sons and daughters who are like my daughters. When they see me, they come to kiss me and want to shake my hand and kiss my head, but I prevent them, and I see the sadness in their hearts, especially when I leave and return. What do you think about this?

Answer:
We see that you are on the right path, and praise be to Allah. You do not shake hands. It is not permissible for a man to shake hands with a woman who is a stranger to him, who is not lawful for him, or who is not one of his mahram (relatives one may not marry). It is not permissible for men to shake hands with women. The Prophet (peace and blessings be upon him) never extended his hand to a woman who was not lawful for him. Rather, he would take the pledge of allegiance from women by words, not by shaking hands. And he said (peace and blessings be upon him)