What is the ruling on sleeping with one's mother-in-law in the same bed, in nightclothes, and embracing and kissing her in front of others?

It is forbidden for a man to sleep with his mother-in-law in the same bed, and it is forbidden for him to enter upon her without seeking permission. This applies to all unmarriageable kin (mahrams). Moreover, his sleeping with his mother-in-law in nightclothes, kissing her, and embracing her are considered reprehensible acts that are not permissible, due to the fear of temptation therein. It is permissible to kiss her only on her head, as there is no prohibition in that.