It is mentioned in the kitaabs that a woman may leave the house without the permission of her husband during a naazilah.

Answer

Naazilah in the context of the mas'alah means a specific issue which requires an immediate answer, e.g. she does not know whether her current bleeding is haidh or istihaadhah; or whether her utterance is kufr or not: or whether the ambiguous statement of her husband is Talaaq Baa-in or not. Thus, if the issue is a Naazilah, and the husband is unable to provide the answer, then she may leave the house without his permission to ask a knowledgeable person.