Here are some possible sources
If you haven’t stumbled on this already , the Anglo German Family History Society. http://www.agfhs.org/site/
Very useful - Meldeunterlagen accessed from the link: www.wien.gv.at/english/history/archives/ancestors.html
Apparently the records cover the period 1904-75 and were compiled by the Viennese police. If you scroll down to click Meldearchiv, you can then fill in the online form provided ( Formular) , giving as much detail as you know to identify the individual : name , approximate
date of birth, profession if possible etc. Children turn up under their parents‘ file. You have to state on the form that it is your grandmother(or grand father etc) to get round the Austrian privacy laws. The search is free but it may take up to two months for a response.
You can ask for up to 5 individuals' entries, and presumably permutations of the name required.
Also might be worth a try . http://www.ihff.at