I think it's pretty obvious that the implication here is even if that is indeed Mom, she is still not the Mom Yuuma knew. For all we know it is more likely that it's either some other spirit larping as her, tricking Yuuma into giving it a body, or it is Mom but she's gotten corrupted by her time in The Warp and became Dark Mom or something to that effect. In the ghost story, Takarada is also presented as having been perverted by her desire for revenge. Others have pointed out that she is implied to have kidnapped and/or murdered the staff member she replaced (Yamamoto), only to then grin psychopathically when her mission is accomplished. Even if her vengeance is justified that doesn't mean she isn't insane. And just like the closing sentence says, the zashiki-warashi will kill its "master" when it leaves the house, so who knows if Takarada will end up living peacefully to old age herself.
The main takeaway from this chapter seems to be "be careful what you wish for".
