You guys need to pay better attention to the story.
The OD’d girl is being buried in the year 2019 (Ohma would have been a literal infant back then).
Also the older woman in this chapter is the maid for the Inazaki family not their mother (the classmate literally makes a whole thing about it).
Also for those who don’t remember, the Toru guy at the beginning of the chapter ends up becoming the director of the orphanage Haruki and Kiriko grew up in.
Which might not be a coincidence, Ishiguro is a big Mother/Earthbound fan and even contributed to a Mother/Earthbound tribute anthology in the past
https://mangadex.org/title/2775d61e-338d-4d7b-a576-c0e011b3708a/pollyanna