Just a note on the burial records online for Mt. Olivet, Mt. Elliott, et al. Your ancestor might still be buried in one of these cemeteries. I found a whole slew of mine in Mt. Elliott that were not listed online as far as I could find. So don't give up.
Did you try filling out the form online at the lookup site? They get back to you pretty quickly.
Also, I had a great-great aunt moved from Mt. Olivet to Holy Cross. Mt. Olivet had no record of her ever being there, even though that is where her death certificate placed her. By pure happenstance I found her husband at Holy Cross and she was buried with him. The records at Holy Cross indicated she had been moved there from Mt. Olivet when her husband died.