Is it permissible for a woman to visit a sick non-mahram man as part of a mixed group of colleagues, or in the presence of a mahram, especially given one of the female colleagues’ emphasis on the reward for such a visit?

There is no harm in a wife visiting a sick woman with her husband, provided that she adheres to the Islamic dress code, refrains from displaying her adornments, lowers her gaze, and avoids speaking in a seductive manner. However, visiting in the company of male and female colleagues is not permissible due to the unlawful mixing involved, which may lead to temptation (fitna).