Is it permissible for an elderly widow to sit in the living room of her house to receive non-mahram male mourners if her son or one of her mahrams is present?

There is no objection to a woman observing the 'iddah (waiting period) after the death of her husband going to the doctor, provided she covers her 'awrah (intimate parts), does not adorn herself with makeup, and is accompanied by a mahram (unmarriageable kin).