I think that rather than the woman representing Yuma's mom, she represents Yuma himself. She wants something and gets involved with the supernatural, which then becomes a problem. Yuma started the ghost stories so he could have his mom back but that has been causing many consequences.
Wants Yuuma to sacrifice his friend for her, caused him to get involved with 2 deaths and an attack... Yup. Would be cool if she just protected him and that kind of stuff, but she seems more like an evil spirit. Causing Yuuma to suffer and killing people so she can come back. Wants him to...