It's a bit like going into McDonalds, buying a portion of fries and expecting (as a duty of care) for them to supply the burger and milkshake for free because you're hungry but only have £1 on you.
EasyJet provided these girls with a flight from A to B (being Southend) at a time when the airport was open. What happens after that is your responsibility IF they have provided you with the goods sold correctly.
I have arrived at Stansted at 4am for a 6.30 departure before and the place honestly looks like Centrepoint at Christmas. Me and the family had to step over a number of 'sleeping bags' in the queue for check-in. It's an airport... Not a homeless shelter.
If you can afford a plane ticket then you should be able to afford a hotel or onward travel. If you can't, you shouldn't be spending your money on plane tickets IMHO.