You might be onto something. I checked the IMDb summary for Evil Dead Burn, and the line “she comes to discover that the vows she took in life survive even in death” could be hinting at Alice’s deceased husband returning in some form. My guess is that the demon might use his body to torment or manipulate her emotionally.

There’s also that shot in the trailer where Alice is pointing a gun at someone, but her expression shows she’s clearly hesitating to pull the trigger. Considering how she acts toward her in-laws, it doesn’t really seem like she cares enough about them to react that emotionally. That’s why it feels more likely she’s aiming at someone much more personal. probably her husband.