Belle tried her best. She thought sending Gideon away would make his life easier. Instead, he ended up rapidly aging while in the care of his evil grandmother. That's a lot to weigh on any mother's mind.
Gideon wants the savior to help him kill his grandmother, the Black Fairy. Naturally, Emma's first response is no way. But Rumple's son can be rather persuasive when he needs to be. Or, he'll threaten her. Again.