The question, although a heck of a mind-bender, seems to be a good exercise for all those MBA wannabes who are preparing for the “Logic” section of the GMAT or the CAT.
Assume some names:
Man in question is: Ram. He is married to Phoolpati.
His sister's name is: Ramkali, who is married to Badlu.
The easiest way to start is to note that Ram's father can be sasur to two people i.e.
a) To Ram's jija Badlu
or
b) To Ram's wife Phoolpati.
Now go one step further and note that Badlu's father can be sasur to his wife Ramkali (who is Ram's sister) and to Badlu's Bhabhis.
Phoolpati's father is sasur to Phoolpati's bhabhi.
1) “Man” and “Woman” in question can be Ram and his sister Ramkali. Because:
Ram’s Father is sasur to Ram’s Jija, Badlu. Badlu’s father is sasur to Ramkali.
The other two solutions are a little tedious but they certainly hold true when examined:
2) The woman walking with the man (Ram) could be his sister Ramkali's "jethani" or "Durani". because:
Ram’s Father is sasur to Ram’s Jija, Badlu. Badlu's father is sasur to Badlu's bhabhis. Note that Badlu's bhabhi would be his wife Ramkali's "Jethani" or "Durani"
3) “Man” and “Woman” in question can be Ram and his wife Phoolpati's bhabhi Angoori. or in other words Ram could be Angoori’s Nanadoiya because:
Ram’s father is sasur to Ram’s wife, Phoolpati. Phoolpati’s father is sasur to Phoolpati’s bhabhi Angoori..