Unless she is part of management and on fixed salary she should be compensated for her overtime. That does not give back the time with her chidren that she is missing. Keep in mind that there are lots of businesses that are run with lots of planned overtime. When I worked in the automotive industry I typically worked 50-60 every week. During one 10 day Christmas shutdown I worked 140 hours.
Harrahs has built their reputation on great customer service. I would hope that when this is over they will somehow reward those who have helped out.