What is the method for treating the mentioned condition, and can one woman cast a spell on eight individuals in one house?

It is not permissible to accuse others of sorcery based on mere suspicion, for Allah Almighty says: "O you who have believed, avoid much [negative] assumption. Indeed, some assumption is sin." [Quran 49:12] This is unless they confess or there is clear evidence. Similarly, it is not permissible to use a cure whose benefit has not been proven legally (according to Islamic law) or empirically, such as burning wool to expel jinn. A person can bewitch or harm several people.