I should have put ca 1915. It was taken between late 1914 and 1915 based on the photos from the same period that surrounded it. I do not know the identity of their patients. Here are some other pictures of them from that album - they are part of the Beinecke Yale Collection.
Tatiana with patients ca 1915
Tatiana and Olga with patients
Tatiana, Olga, Anna Vyrubova, and Alexandra with patients
Tatiana, Olga, and Alexandra with patients