I took a trip over to the Firefly page on My Little Wiki, and while there wasn't anything definitive, I'm guessing she may have not come with one. I believe ribbons became less standard toward the end of the G1 line and this Firefly may have not come with a ribbon, especially given she was packaged with a videotape. I haven't seen an MOC up close enough to say for sure though.
Hopefully someone else knows 100%!