Presidents and First Ladies Trivia

[L Verge]

Good guesses both of you, but not correct. Hint #2 - The number of numerals in the full Roman numeral on the gravestone will tell you which President he was. There are four.

XVII - Andrew Johnson, the 17th President.

Another good guess, but not correct. Keep eliminating via considering the number of times four Roman numerals are used to give an actual number.