In A Quiet Place Part II, Cillian Murphy's character, Emmett, has suffered the loss of his family at the hands of the alien monsters, and his method of coping involves keeping his wife's dead body and drawing his son. His apocalypse experience was arguably more devastating than that of the Abbott family, once his friendly neighborhood companions. The depths of his depression are slowly revealed in Krasinski's sequel, as the Abbott children find remnants of his family all over the compound, literally and figuratively.
In 2018's A Quiet Place, the Abbott family lives a relatively comfortable life, adjusted to the unique sound-oriented dystopia, mourning the loss of the family's youngest some months prior. While the first film focuses on their struggles just over a year into the after-times, A Quiet Place Part II's opening reveals their prior relationship with Emmett and his family. Unlike the Abbotts, Emmett's family didn't remain nearly as tight a unit, with Emmett losing his only child the very day of the aliens' arrival and his wife to a slow, painful illness sometime later. These tragedies lead him to adopt a nihilistic and defeated lifestyle as a recluse until he is shaken from his depression by Regan's determination. Regan and Marcus each learn more about Emmett through his late family members—sometimes in surprising, horrific ways.
Emmett draws his son's face compulsively; his artwork is strewn about the rail station dwelling for Regan to find when the Abbotts are saved from near disaster early on. In a world where technology has failed, the only pictures of loved ones are the ones people were able to rescue from their likely-destroyed homes. Drawings provide the only way to fix memories in a tangible form. His drawing his son is a means of preservation, a way to ensure his deceased son lives on in his memory without fading over time. It demonstrates visually his having not moved on, elegantly establishing his dour psyche which Regan must overcome in A Quiet Place 2 in order to save humanity.
It also provides his character with an added dimension, making the audience question his sanity ever-so-slightly. During the terse intercut sequence at dusk, Emmett proves himself chivalrous and not beyond saving, even offering help to a little girl who is eventually revealed to be bait. But meanwhile, Marcus goes exploring the rail yard, and he is shocked when he finds Emmett's late wife rotting in bed, long since passed from the world. The beat shows that Emmett couldn't stand the loss of his wife so much that he refused to lose her at all, instead keeping her body close even as it wastes away. As a physical survivor in A Quiet Place 2, Emmett is more than capable, but as an emotional one, he's clearly not handled it well or in a stable way.
Or perhaps instead there's a simple practicality concern to this. It's said he brought her to the rail compound because of the screaming pain her illness caused, and he kept her in the sealed chamber where she wouldn't alert the monsters. Maybe he left her up in the rafters to bring a swift end to her suffering. He might not have removed her because of the sound such a proper burial service would inevitably cause. There's no evidence he's been revisiting her corpse or displaying any truly deranged behavior.
Whatever the specifics of the situation, it's clear that Emmett succumbed to the weight of these two losses when the remaining Abbotts stumble into his compound. The constant presence of his late family members, whether their faces in drawings or their corpses in rafters, underscores his hopelessness. They function as visual shorthand for his mental state and backstory, providing the second act with more thrills, while also establish Emmett's starting point. By the end of A Quiet Place Part II, he has put aside these tragedies and learned to hope again thanks to Regan.