All three stations (which serve most trains from St. Petersburg, as well as Trans-Siberian services from Beijing and Vladivostok) are located on Komsomolskaya Ploshchad, around 5km by road from the Marriott Grand Hotel.
By taxi
It is a short drive to the Moscow Marriott Grand Hotel, and should take no more than 20 minutes, in moderate traffic. Taxis should not cost more than $20, and you can also pre-book a transfer with a driver to meet your train here.
By metro
All three stations are connected to Komsomolskaya Metro Station. From there, take the brown circle line and travel three stops anticlockwise to Belorusskaya. Change there to the dark-green line and head south one stop to Mayakovskaya, which is less than 100m from the Moscow Marriott Grand Hotel.