Is it permissible for a woman observing 'iddah to leave her home for her brother's house during the 'iddah period, given that she has adult sons?

The basic principle is that an 'iddah-observing woman should not leave her home except for a necessity, such as selling or seeking medical treatment. Some jurists permitted her to go out during the day for needs, and a few allowed her to go out at night, though preferring that she not do so. A condition for her going out is that she avoids adornment and does not spend the night outside her home. Therefore, it is not permissible for an 'iddah-observing woman to go out to visit her brother, as this is not a necessity. Instead, her brother should visit her in her home.