Is it permissible to shake hands with a female colleague's mother if she is over fifty and he is the age of her son?

The ruling on shaking hands with a woman is not based on her age, but on whether she is desired. As long as a woman desires or is desired, the ruling concerning her remains the same. Allah Almighty restricted the concession for "women past childbearing age" to those "who do not expect marriage," meaning they are not desired by people. If a woman reaches a state where she neither desires nor is desired, there is a difference of opinion among scholars regarding the permissibility of shaking hands with her. The preponderant view is that it is forbidden, due to the generality of the evidence, and this is the most cautious and most absolving for one's conscience.