Arrived in USA in 1887 - Have you searched the 1900 Census -as well others following
When was she married ? - Registration of Marriage - may show age - place of birth- names of both parents - depends on requirements of the time
Depending on her year of Birth There may not be official Registration of Birth
BAPTISM - what religion did the family follow ? - Catholic .
Finding Catholic Church in Simcoe - the records should be available - perhaps archived
How old was her husband - he was the Informant for her Registration of Death. They may have been fairly close in age
Were there any children - their dates of birth may help determine the Age of Jennifer
When / Where - did her husband pass away ? -
It is possible that the information on the headstone is not correct
Stone mason - or ? - may have made an error -that was not noticed at the time