Question :
                                            
                                            
                                            
                                                Is the father a Mahram (Non-marriageable) to his son`s mother-in-law?
                                            
                                            
                                            The Answer : 
                                            
                                                The father is a non-Mahram (Marriageable) to his son`s mother-in-law, so it is impermissible for them to look at each other, or to have a seclusion (Khalwah).