You are now standing at one of the entrances to the Adams Memorial, one of DC's hidden gems.
This monument, designed by Saint-Gaudens, was erected in 1891. It was commissioned by Henry Adams as a memorial to his wife, Marian "Clover" Hooper Adams, who had committed suicide through the ingestion of potassium cyanide. Adams asked Saint-Gaudens to cast a memorial representing the Buddhist idea of nirvana where there is no joy or sorrow. Adams, who traveled to Japan to find inspiration for this memorial, particularly wanted elements of serenely immovable Buddhist human figures to be contrasted with the waterfall-like robe associated with Kannon, an iconic image from Buddhist devotional art. In addition to the still and flowing elements, the monument's dualism includes male-female fusion in the figure itself and blends Asian and European ideals of figure. These checks to the standard heroic figure combine to make a "countermonument" for a woman who disliked monuments generally. On March 16, 1972, the Adams Memorial was listed on the National Register of Historic Places.
Adams instructed that there not be any inscription at all on the memorial. So stand with your back to the memorial and face the bench. At the end of each bench is a claw with talons. How many total talons do you see? This is the answer for A.
N 38° 56.883 W 77° 0.681 - Rabboni
As I left the Adams Memorial, I wasn't feeling particularly moved or overwhelmed (people have been known to spontaneously burst into tears). I wandered along until I saw this monument.
This monument spoke to me. I felt like the woman from the Adams Memorial was keeping a secret (perhaps why she committed suicide) but this woman was desperately trying to tell me something. Thanks to a more than a little searching on the internet, I was finally able to figure out what. This sculpture, by Gutzon Borglum (the sculptor famous for creating the presidential heads for Mount Rushmore, depicts a Mary Magdalene emerging from an alcove consisting of three granite blocks taht surround her. Dressed in long robes and a cape which covers her head, her right hand is raised to lift the cape from her head. Her left arm is extended outward in front of her. Her proper right leg is stepping forward, to recognize Jesus Christ has risen from this tomb on Easter.
Now walk around behind the memorial. You will see two bronze plaques. The lower plaque states that this is in memory of how many people? This is the answer for B.

N 38° 56.819 W 77° 0.727 - Cramphin Grave
You are now standing near St. Paul's Episcopal Church. The oldest graves in the cemetery are all found within 100 feet of the church. You are looking for the grave of Elizabeth Cramphin. Her grave is the oldest in the cemetery on which the inscription is still legible (I've already found the 2nd oldest once nature takes its toll on this one). The grave not only lists the month and year of her death but also her age. Subtract the second digit of her age from the first digit of her age. This is the answer for C.
N 38° 57.006 W 77° 0.554 - Russian Orthodox Grave

You are now standing in one of the sections reserved for use by members of the St. John's Russian Orthodox Church. This particular section also contains a chapel for use by the Russian Orthodox Church. The Chapel "was consecrated on September 10 by His Eminence, the Very Most Reverend Metropolitan Laurus, First Hierarch of the Russian Orthodox church Outside of Russia."
A few rows in front of the chapel, you will find the grave for Princess Dorothy Galitzine (unfortunately I have not been able to find much information about the princess). Looking at her grave, make note of the last digit in her birth year. This is the answer for D.
N 38° 56.B6C W 77° 0.AD3 - Final Stage
Now head outside of the cemetery for quick walk to the final stage to sign the log book. The cache container is found at:
N 38° 56.B6C W 77° 0.AD3
- A = total number of talons on the claws at Adams Memorial
- B = number of people memorialized on the plaque at Rabboni
- C = Elizabeth Cramphin's age at death, (first digit - second digit)
- D = last digit in Princess Dorothy Galitzine's birth year
Congrats to zorrobarnes for first to find!