135:15 Women are exempt from this mitzvah but they are nevertheless permitted to recite the bracha if they choose to eat in a succah. Children are likewise exempt but a father has an obligation to teach every child from the age of five and up to eat in the succah. Even if his father is not at home, a child should not be permitted to eat outside the succah. (Some say that if a child has no father, then his mother and the local beis din assume the responsibility to educate him in the mitzvah of succah – Mishnah Brurah 640:5.)
135:16 A sick person (for whom eating in the succah is difficult – MB 640:9) and those caring for him are exempt from eating in the succah. If he is not dangerously ill, those caring for him are only exempt when he actually needs them. (If there are two people caring for him and he only needs one at a time, they should takes turns eating in the succah and caring for the patient – MB 640:10.) If the patient is dangerously ill, they are exempt even when he does not need them all that much.