Could be, but in the previous chapters Haru explained that his mother was bedridden, so I think she definitely was alive at that time, at least he would be aware that the mother is not here but he can see her, otherwise he wouldn't be talking about her as if she is alive. Also, he only started to see ghosts recently, as Taya told him, you hang around the supernatural, you start to see it more.
My guess that the mother is a ghost now, and she died while Haru was away, and he didn't know, since he went radio silence with his family. I still wonder what exactly happened to her that her face got those scars, she was bedridden and unable to speak, AND his father would blame Haru, an infant at that time, for this?
P.S. A guess: Haru caused a fire in their house as a kid, mother saved him from the fire, but suffered burns and carbon monoxide poisoning, and left bedridden after that.