Stones aren’t always correct.
This stone has a date of death for the wife that differs from the date of birth listed on her guardianship in the 1850s. The stone is transcribed as written–I don’t change what something says.
But the guardianship record is more contemporary to Franciska’s birth and the informant on that record is likely her mother.
Based on estate records for husband John, this stone was erected after his death in 1917–some time after Franciska died with information provided by someone who did not have first hand knowledge.
I indicate exactly what the stone says, but for I would give the most credence to the date of birth from the record that was created most closely to her actual birth.