Is it permissible for a man to marry his son's wife's mother or his son's wife's sister?

The mother of the son's wife is not a mahram to the husband's father. However, she is a mahram to her son (her daughter's husband) because she is his wife's mother. This is based on the Quranic verses that define the forbidden women in Surat An-Nisa, where Allah Almighty mentioned the forbidden categories and then said: "And lawful for you are [all others] beyond these."