The closest relationship between Nicholas II and Q Victoria is 2nd cousin 3 times removed, through Duke Charles II of Mecklenburg-Strelitz and Elizabeth of Saxe-Hildberghausen.
That also makes them both cousins to the Prussian royal house, as Kaiser Wilhelm I was Duke Charles's grandson. So Kaiser Wilhelm was Q Victoria's second cousin, and Nichols II's great grand nephew. Nicholas's great grandmother was Kaiser Wilhelm's sister Charlotte, who married Grand Duke Nicholas, later Tsar Nicholas II. Wilhelm and Charlotte's mother was Louise of Mecklenburg-Strelitz, Duke Charles II's daughter, who married Friedrich Wilhelm III of Prussia.