I do not have a subscription to Filae, but I found the record anyway, by browsing the alphabetic tables. It is not the actual record, but a transcription of a record from Neuilly-sur-Marne (93), which is not online and not even at the archives départementales, but still at the city hall.
Lydia Maximilienne Härstedt died at 26, on 9 Sep 1939, in Neuilly-sur-Marne, and the record was transcribed in Paris 11e arrondissement, where she lived (that's how I found her without looking through all arrondissements: the address is the same as on her father's death record). Reference is: Paris 11e, registres d'état-civil, décès 1939, n° 2031, Archives de Paris cote 11 D 335. There is no direct link to the document. You can obtain it from this form, with the following data: type de document = décès, arrondissement = 11, année = 1939, date empty, numéro = 2031. Then it is on image 20/21.
It does not give much information, and in particular does not specify whether her parents were still alive or not (we know her mother was), or whether she was married (she probably was not).