Hopefully they got to high ground for shelter. They don't need to fully evacuate, but finding a sturdy multi-level concrete parking garage, a well built multi-story public building (hospital, school, etc...) is enough so that they would be safe.

Nobody expected a borderline Cat-5 hurricane... but here we are. A Cat-3 would be relatively safe to stay for, even at elevation of only 10 feet +/-. That's what they were originally projecting. A Cat-5 is an entirely different story. Sturdy building well above 20+ feet above sea level is the only place to be safe other than evacuation. Unfortunately, the storm ramped up in windspeed so quickly that there wasn't time for people who chose to stay... to re-consider.

Always know that you don't have to go 200 miles inland for safe shelter. Most often, you can find safe shelter in office buildings, or civic buildings, hotel parking garages and other things. Don't be afraid to break a few rules (or a window, door, turnstile) in order to find safety from the storm. You can always apologize later. Meanwhile, if you find yourself sheltering in a large office building or a public official's building... remember to find the most important person's office and then put your muddy feet on their desk. You get so few chances to do that in this life... so take advantage.