I waited a beat to drain the exasperation from my voice; to remind myself that she’d lived in this house for 45 years, that moving is a major traumatic event for anyone—more so for those as change-resistant as my mother. “He meant don’t sell it right away; not right after he died,” I said. “He didn’t mean not to sell it when you’re 85.”

“I guess,” she said, which only meant that she’d heard me, not that she agreed. I assumed this conversation had dead-ended, as so many before had when the subject of selling the house and moving to a nearby senior housing development came up. But she surprised me a few days later by telling me she’d engaged a real-estate agent who was coming over on Saturday.

Red-haired Ruth, friendly and perky but all business, younger than my mother but older than I, strode into the house with an almost military bearing—even her cream-colored scarf accenting her navy blue pantsuit looked crisp. She exuded confidence that the three-bedroom suburban ranch in an excellent school district would sell in a heartbeat. “It’s practically market ready,” she said, inspecting each room, my mother and I, lowly sergeants, following in her wake.

“Put the tea canister in the cupboard,” she said in the kitchen, “and get rid of that basket. Keep the detergent under the sink....” My mother wrung her hands; I jotted down her every instruction, trying to hide my…