here is my suggestion:
you must plan for the taxi, as touta said, because probably you will arrive too late.
i suggest since you are alone, you go to l’auberge de jeunesse. it is an internationally-affiliated youth hostel, maybe you can meet some other travelers; it is cheap.
i think it is a good option for you because even though it is inside the medina, it is just next to the wall on the seaside, so very easy for a taxi to take you very close.
bad, achminfar9 directions :
you will be coming from south of casablanca with the airport, and this area is right next to the northern ocean border of the city. if he does not know how to get to the auberge, you can tell him the bvd almohades…this is the big street that goes between the coast of the ocean and the medina wall. with the medina on your left and the ocean on your right, eventually this road would lead to la squala, an old fort with cannons (now a restaurant) and then it would come to hassan II mosque. if you see this fort, or the mosque you went way toooo far. the door you want is maybe 500 meters before the fort. this is a door in to the medina that is right next to the auberge, but it’s not labelled on google maps sorry.
i think he will know, and anyway he can ask some people no problem on the way. at the worst, he will drop you on the wrong side of the medina (where you see the old downtown of casa leading in to the medina and you cant see the ocean. then you go to the medina door and you ask someone who looks like they can help.
i find this area of casa medina to be very safe, much better than the streets around marche central, downtown casa.
the staff is very friendly to girls, not so friendly to guests like me :).
here is the address, phone number, email. even if you don’t make a reservation, and they tell you they are full, there are a few slightly more expensive hotels next to the auberge with always open rooms.
6 Place Ahmed Al Bidaoui