The wife is the inspector's wife, the son's mother, and the mother-in-law's daughter.
She becomes sick without food in 2 days and without heat in 3 days. Her sickness threshold is 5, the highest among all family members. Just like everyone but the inspector, she gets hungry, sick, very sick, cold, and possibly dies.
If alive at the end of day 29, the wife finds a family photo. It can be hung on the wall of the inspector's booth but having it on the wall on day 30 can lead to ending 11.