die, bury
殪 centers on death and its aftermath: dying and being buried. The two given meanings are directly connected as the end of life and the disposal of the body.
殪 combines 歹 (death) with 壹, which likely contributes the sound. The character is associated with dying and burial, but the exact historical development of the right component is uncertain.
The left side 歹 represents death, and the right side 壹 looks like a sealed container. Picture a dead body being sealed in a coffin and buried.
For エイ, imagine an eerie 'A' sound echoing from a grave: 'A' -> エイ, as the buried dead let out a ghostly wail.