Mrs. Olubunmi Odumusi, 57, died in her sleep, last night, Friday, September 2.
Relatives said she died after a prolonged battle with cancer, after being treated local and foreign hospitals at a huge financial cost.
Her heartbroken husband wept, clasping the body of his departed wife.
She was in the U.S for medical treatment when she received the news of her promotion as Permanent Secretary.
She flew back to attend the inauguration and attended the event on wheelchair on Thursday.