St. Emerentiana has a rather thin entry in the 2005 Roman Martyrology:
2. Romae via Nomentana in coemeterio Maiore, sanctae Emerentianae, martyris.
There is a rather "hagiographical" account of Emerentiana. According to the story, Emerentiana’s mother was the nanny of St. Agnes, perhaps her wetnurse. Thus, Emerentiana and Agnes would have probably spent quite a bit of time together, perhaps even being like sisters to each other. Emerentiana was a catechumen. A few days after Agnes’ death, listed in the depositio as 21 January, Emerentiana was found praying at Agnes’s grave. Though not yet baptized she declared herself to be a Christian. They stoned her to death. She was placed in the same tomb as Agnes, close in death as they were in life.