Is it permissible to shake hands with the wife's maternal grandmother (her mother's mother) or paternal grandmother (her father's mother), the wife's paternal aunt, her paternal uncle's wife, and her maternal uncle's elderly wife?

The wife's grandmother is a mahram to her daughter's husband, so it is permissible for him to shake her hand, whether she is the paternal grandmother or the maternal grandmother, due to Allah's saying: "And your wives' mothers" (An-Nisa: 23). This includes every female who gave birth to the woman. As for the wife's paternal aunt and the wife's paternal uncle's wife, it is not permissible to shake their hands because they are ajnabiyyat (non-mahram). As for the elderly maternal uncle's wife, shaking her hand is a matter of dispute among scholars, and the safer course is not to shake hands.