Autumnal Threat

A science-fiction short story involving: an alien autumn, an unseen predator, deadly burrowers and an oncoming winter, and bugs big enough to ride. Joaquin only wants to warn his daughter of a new danger, to keep her safe, to make her understand her mother isn't coming back, while keeping her alive. But what if he's wrong? What if Mariam really did survive? What if, when everything looks like it's going wrong, it's really going right?