Obviously, someone from the senior staff who can call on and demand a leave of absence from her staff and company. However, still thoughtful enough to let everyone know of her personal situation.
I am currently in a conference trip in [place] representing our company at the annual [event]. Unfortunately my husband has fallen ill at home and I am returning a day earlier than planned. Please have someone in the staff arranged for my flight home, as I would like to turn over my work responsibilities at the office before I head to the hospital. Also please note, my sudden leave of absence for the next three days.