* This person is not publicly known. Perhaps they were not a public figure or had a very private life.
* The information is incorrect or misremembered. It's always possible for names and details to be confused.
* There is no public record of their death. There are many reasons why a death might not be widely reported or documented.
If you have more information about Antonia Hilke, such as a possible date of birth or location, it may help in finding more information about her.