Board Thread:Questions and Answers/@comment-2163079-20130502022253/@comment-41.97.60.145-20141222130139

Lelouch's driving emotions were hatred towards Britannia and love for Nunnally. He had two purposes, each one for one emotion. The first was to destroy Britannia to get revenge for his mother being killed, and him and Nunnally being abandoned. The second was to create a gentle world where Nunnally would have a future instead of hiding in fear of being assassinated or used as a political tool. These two are the oaths he swore as he made a contract with C.C, and it was the purposes the witch was willing to help him with, so she would grant his wish in exchange for him granting hers. (though we can see that she mostly manipulated him since she knew his mother's murderer all along and kept silent so he would cause enough destruction (to the world and mostly to himself) to be able to kill her someday.)

As an emotionally unstable character, Lelouch always saw his revenge against Britannia and making Nunnally happy tightly linked. Britannia took everything from them, after all, including their mother, their home, their happiness, and Nunnally's sight and legs. And in a less emotional way but still as subjective, he thought that Britannia stood against peace and that the only way to get a gentle world was to destroy Britannia. Little did he know that there were some people who actually wanted to change Britannia from within, and that only his hatred made him think that it was a matter he could only resolve with force. (when he realizes his mistake, it's already too late. Euphemia could at least make him realize that he was only blinded by his revenge wish)

So. To answer the question. At the end of the series, the one who killed his mother is burried deep underground, and his sister became the Empress of Britannia. So yeah, he definitely accomplished both of his wishes. In the official guidebook, it was said that by knowing that Lelouch didn't hate her, C.C could go with her life and discover the future she has been given with the world, no longer feeling as lonely as before, and it was implied to be her true wish. So we can say that both ends of their contract had been met.