Looking for Imformation on Jacob Hiltner B 1816 17 IN Darmstadt Hesse

Looking for imformation on Jacob Hiltner B:1816-17 in Darmstadt-Hesse,Germany and Elizabeth (Fernau/ Fairnow) Hiltner B:1832-33/ 1822-1828 in Darmstadt-Hesse, Germany. Jacob D:1881; and Elizabeth D: 1888,both died in Frederick,Frederick Co.,Maryland. Can not locate graves. Anyone with imformation on them please contact me. These were my ggggrandparents. Thank you. Pat