Seedfork!
Daylily (Hemerocallis 'Moon Over Miami')
I see by the registration information that it blooms mid-late, is 20" tall and 4-1/2" bloom. Those might be things you can check - 20" is pretty short, 4-1/2" is on the small side, and mid-late is a little out of normal range. "cream yellow with rose eyezone and green throat" description might fit what you have. It is old enough, that photos were not required for registration and also few people would still be growing it.
Since your Mom had that name for it, I'd check the bloom height and size, and when it blooms according to when other daylilies bloom in your area and see if it matches the registration info. If it does, then it may be Moon Over Miami.
Unfortunately, you may never know for sure.
