Death scene? Are we reading the same story? Because she's alive and healthy here. But yes, the author is absolutely the worst at endings.
The last panel pans to a portrait of the mom. Before that, the dad reminisces about her both verbally through reading the story to his daughter and mentally through flashbacks to the moment before the flash forward.
During which the author parallels the daughter’s appearance and behavior to the mother, making it seem as though he’s having this recollection because he’s reminded of her.
People don’t have recollections of alive mothers through their daughters; you don’t need to be reminded of the image of your wife and the mother of your child if she’s still constantly in your life.
And even if you do, it’s not going to be to this exact moment right before a time skip that is for some reason being immortalized in a portrait that the author felt the need to pan to in the last panel.
All while the mom is entirely absent and referred to (metaphorically) in past tense.
Look, is it explicitly stated? No. But put yourself in the author’s shoes and assume they’re writing that she died; no author is going to present death by blatantly stating the wife died halfway through the chapter.
They’re going to use subtextual ways to show that she died (they’re going to imply her death), so that they can romanticize her passing and utilize it as a moment of introspective reflection of the character and “her beauty”.
And if you look at the subtext, it’s about as obvious as you can get. All the subtextual clues with the flashbacks, flash forwards, and the portrait are textbook tropes for implied death. Like this is the premier formula for saying someone died without saying someone died lol.