[Ger-Poland-Volhynia] varying dates

[Annegret Krause]

Another possibility:
 
The difference between the birthdates could result from the differece
between the both calendars + a transcription error:
Maybe they mixed March up with May.
In this case your grandmother's birthdate was March 5th 1844 (Gregorian
calendar) or  February 22nd  1844 (Julian calendar). 1844 was a leap
year.
 
The difference between the death dates I can't explain.
 
Annegret