The fifth day would take my group from Karanga Campsite (13,400ft) to Barafu Campsite (15,800ft). This will probably be the shortest day of actually hiking for you as this is the day before summit day. You will be hiking across a ridge for most of the day, and the trail is pretty easy going. You do gain over 2,000ft though, so it isn't a walk in the park by any means.
The remainder of the day is basically just for resting, acclimation, and getting your gear ready for summit day. Barafu Camp is pretty spectacular in its own right, so be sure to soak in the views.
Pre Summit Preparation
Summit day will be the most challenging day of the trip. It is long, it is cold, you are tired from 5 days of hiking, and it is physically tiring as you will gain almost 4,000ft. You should take the rest of the day to relax and sleep if possible. Our group ended up getting up at 11:30pm, but it is incredibly helpful to try and get a couple of hours of sleep. In terms of gear that you need, you will need your headlamp and poles, and some parts of the trail can seem tricky in the dark. You are also going to want to layer, as it will warm up a great deal once the sun comes out. Your layers will depend on the weather you have. We had perfect weather, so I wore a base layer (underarmor in this case), a mid layer which is just for warmth, and an outer layer for wind (and rain) + warmth. You are also going to need gloves and your cold weather boots, if you brought two different pairs. It also probably wouldn't hurt to slip a hand warmer in both of your gloves and boots if it is comfortable. I did, and my feet and hands were perfect the entire time. We only saw temps in the high 20s, so it wasn't too bad, but just be aware that it can get extremely cold. Also, if you have an ipod, this is a great time to use it. Other than that, it is the best day of the trip! Get ready.