"Would they throw muslim woman with 3 kids on the road" - I have to laugh, sorry. You are safe regardless you are or not a Muslim woman.
But why you not stay at hotel somewhere in Fes, you have anyway to go to the train station so take you at some room, sleep well and next day continue to Casa instead to stay at airport over night.
I am in agreement with Khamlia.
Reserve a hotel room in Fez with 3 beds, for the night of your arrival and be sure to let hotel management know that you will arrive late. Ask them to send a car pick you up at the airport!Edited: 19 May 2017, 15:48
There are many inexpensive hotels in Fes and there is an Ibis hotel next to the station. Why expect three children to spend a sleepless and uncomfortable night in an airport rather than in a proper bed?
In addition, the night train is perfectly safe whether one is a Muslim woman or not.
Budget for a hotel or take the train. If your travelling alone sleep where you want. Traveling with kids, don't put them through that when you have options, eg a hotel. Be responsible.
You can hire a cab outside of the airport and go directly to the train station. You will find a train to go directly to Casablanca. You can rest in the train as it is safe.