Will your friend tuck the quilt in at the foot of the mattress? Does she have an extra thick mattress? I have one mattress that is 14" thick and one that is 17" thick and I tuck everything in because I want my bedskirt to show.
When I sleep I leave everything tucked in at the foot or my DH pulls everything out and away and tosses it like a hurricane! LOL! So my bedding has to be larger than normal. 100" would not be long enough for me.