Genie wanted to. She really did want to. But there was no way to twist the wish in her favor. So she ended up granting her master's last wish just the way she wanted. Claire's mother was no longer sick with cancer. (Using her new witch powers, Claire had retrieved her lost memories of being a 20-something woman and discovered that her mother was sick with cancer.)
She expected to be forced back into her lamp. After all, Claire had used all five of her wishes. So she was no longer her master and there was no reason for Genie to be out of her lamp. But nothing seemed to happen. Despite the logic of the situation, Genie wasn't being forced back into her lamp.
"Why are you still here?" Claire asked.
Genie answered, but it was more like an automated response, not her own thoughts on the situation. "You have five wishes, Master."
"What? I thought you said that I could only have five wishes. Are you telling me that I actually had ten?"
"No, Claire. I'm speaking to my master - Olivia Harrison."
"Olivia?! She doesn't exist anymore!"
"You're wrong, Claire. She exists within you. She is my new master. And I await her five wishes."
Claire stared at Genie, her mouth wide open. What the hell was this? Could Olivia really still be there, deep inside her own head?
"Master," Genie spoke to Olivia. "Please tell me your wishes."
Claire opened her mouth to say something, but what came out of her mouth weren't her words. Instead, they were the words of Olivia Harrison. Now she was in control of Claire's body, which used to be her own just hours earlier.
In a sweet but shy voice, Olivia said "Thank you for helping me speak, dearie. I wish ..."