The name Hilma is a girl's name meaning "protective helmet". Hilma and discussed in our forums with posts like "Heaven, Hell, Purgatory -- Girls Names 900-1000".
From the experts:
Hilma is heard in Germany and the Scandinavian countries, and sometimes used as a shortening of Wilhelmina--though there are more appealing German names for girls. to be found. Hilma Wolitzer is an American novelist and the mother of author Meg Wolitzer.