To be honest, I'm not sure that I'm correct, about 1899 as a date, but I do have doubts about 1901: If this picture was taken at Wolfsgarten, it cannot have been taken in 1901, as Nicholas/Alexandra did not visit Hesse in 1901, as far as I know.
According to Nicholas' diary, Nicholas and Alexandra attended a memorial service, Panachida, at the Russian Orthodox Church in Darmstadt on 28 September (old style date) - 3 months after GD George's death.