Letters of St. Joseph of Optina
Your Mavra, as it can be seen from your description, is in delusion. - What to do? It happened and is happening sometimes here as well. Our deceased elders recommended menial jobs for such deluded persons. As delusion is a result of pride and conceit, the damned pride is reduced, at least to some extent, through menial jobs. You should make Mavra help in your kitchen with anything she can, for example, cleaning potatoes or washing the dishes, and so on. She should not be allowed to lead a solitary life under any circumstances. For, as you have noticed, she will become crazy. She should not take the Holy Communion often as well. Let the confessor first to persuade her to humility and self-abasement.
Novice Evstolia, a prayerful person, is afraid of falling into delusion. - Let her keep the God-pleasing humility, believing herself in her heart to be the most sinful of all the persons, and then she will not fall into delusion. For, according to the remark of Holy Fathers, "humility cannot fall".