Found a Nicolaus Schnell in the Castle Garden arrivals list. He arrived on November 24, 1891, and listed his destination as Baltimore
He gave his age as 33 (so birth ca. 1858), and his profession as "farmer." His last residence was in Norka, Russia.
Grandma was born circa 1880; her father's name was Nicolaus. I know he died in Russia; it is possible that this Nicolaus is a cousin. The Schnells were a large tribe in Norka.
Other Schnells from Norka through Castle Garden:
Peter Schnell, 29 (born circa 1861), arriving 28 Nov. 1890, ship Polaria, destination NYC
Heinrich Schnell, 20 (born circa 1870) , arriving 28 Nov. 1890, ship Polaria, destination NYC
Johannes Schnell, 20 (born circa 1867) , arriving 6 Dec. 1887, ship Anchoria, destination NYC