From Miranda Carter's George, Nicholas and Wilhelm: Three Royal Cousins and the Road to World War I (2009; p. 410-11):

There were rumours that the German terms of the Treaty of Brest-Litovsk included a demand that the imperial family must be handed over to Germany unharmed. Nicholas had not been able to bear the thought: “This is either a manoeuvre to discredit me or an insult.” The rumours were not, as it turned out, true. In Moscow, Nicholas’s old court chancellor, Benckendorff, brother of the former British ambassador, tried to get the German ambassador, Mirbach, to support a rescue mission. In Kiev, now occupied by the Germans, Mossolov attempted to persuade the German commanders to back a plan to travel up the Volga to Ekaterinburg. He wrote personally to the kaiser about it. He never received a reply. A former German ambassador to Petrograd told him with much embarrassment that the kaiser couldn’t reply without consulting his government, and the local German commanders refused to help.

After the war Wilhelm swore that he had tried to get the tsar out. “I did all that was humanly possible for the unhappy Tsar and his family, and was seconded heartily by my Chancellor,” he told General H.-H. Waters, whom he’d known as a British military attaché in Berlin, in the 1930s. He said that Bethmann-Hollweg had come to him with a Danish plan for rescuing the tsar. “How can I do that? There are two fighting lines of German and Russian troops facing each other between him and me!” Wilhelm quoted himself. “Nevertheless I ordered my Chancellor to try and get in touch with the Kerensky government by neutral channels, informing him that if a hair of the Russian Imperial family’s head should be injured, I would hold him personally responsible if I should have the possibility of doing so.” In Wilhelm’s version, Kerensky answered that he was only too happy to provide a train. Wilhelm said he had informed Bethmann-Hollweg he would order the High Commander on the Eastern Front to arrange safe conduct for the tsar’s train, and told his brother Heinrich to escort the ship holding the tsar through the minefields. “The blood of the unhappy Tsar is not at my door; not on my hands,” he told Waters, though why this foolproof plan had failed he was unable to say.

What Wilhelm certainly did do was give his permission on 24 March 1917 to allow Vladimir Lenin—a man more radical than any German Social Democrat—to travel via Germany to Russia, with the explicit intention of creating as much chaos and destabilization in Russia as possible.

[Original emphasis]

So, much as was the case with George V, there was a great deal of self-exculpatory outrage after the fact but little that seems to have been done about the matter when it was still possible to prevent it.