Mary Mertz d/o Peter married John Douty in 1799. I'm assuming this is she.

There is a memorial for Mary and John Douty on find-a-grave at the Center Lutheran Church Cemetery own Montour County. She died in 1845, he in 1848. The tombstone, though, based on the photo, appears to be much newer than 1840’s.

Richard J Martz refers to this burial too as “in an old cemetery along Route 45 in Montour County.”