This name may sound strange to many of us, but students of Medieval Russian history will certainly recognize the name of the famous Grand Duke of Kiev, Vladimir Monomahk (1053 - 1125). VM founded the city of Vladimir and is widely associated with the Golden Age of Kiev, and was the link (because he was grandson of the Emperor of Byzantium) of the Russian Empire to the Byzantine in political mythology. (Students of British history may know that his wife was the daughter of Harold Godwin and Edith Swan Neck, the former being the ruler overthrown by William the Conqueror).
In Russian tradition, the line of descent from a famous person was often memorialized by a new surname. In this case, it is very likely that the gentleman buried in New York was a descendant of Vladimir Monomahk.
I found this little tidbit on MySpace, which was a list of resistance to the Bolsheviks from 1917:
June 7th, 1927: The mission of terrorists of the Russian All Military Union into the USSR. The group of Larionov, Soloviev, and Monomakhov throws a bomb at the party club of the Leningrad communist university, wounds 26 people and escapes into Finland; the group of Maria Zakharchenko-Schultz, Voznesensky, and Opperput tries to bomb the housing facility of the OGPU in Moscow but is discovered and killed in a gun battle. On that same day in Minsk the head of the Belorussian OGPU Opanskiy is killed by unknown assailants, and the 17 year old Boris Koverda kills the Soviet political ambassador Voikov at a train station. The reason for these actions is to destroy the myth of the all-powerful GPU, which had been widespread after their provocational TREST operation of the 1920's.
Finally, Monomahk's Cap is a very famous part of the Russian Crown Jewels and presently resides in the Kremlin Armory in Moscow. It is the oldest crown in the collection