is it permissible for someone to marry his step motherinlaw who is now divorced from his father inlaw?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

It is permissible for a man to marry the wife of his father-in-law if the father-in-law has separated from her and she completed her waiting period from him because there is no family lineage between him [the man] and her. In principle, it is permissible to marry any woman unless there is evidence that it is forbidden. Imaam Ash-Shaafi’i said: “It is permissible for a man to marry at the same time a woman and her (ex) step-mother; many scholars of our school of jurisprudence said this.”

Since it is permissible for a man to marry at the same time a woman and her ex-step-mother, then it is more appropriate for him to marry the step-mother of his wife after having separated from his wife or after her death, because since it is permissible to combine (in marriage) a woman with another woman, it is permissible, with greater reason, to marry her separately.

Allaah Knows best.