Hard to tell from photos how large the snake is. Check any plumbing pipes that run into walls or down through floors for gaps large enough to allow passage and plug same. Keep toilet lids down! Dishwashers often offer a crawl space and warmth... Place mouse in wire cage on floor along a wall or in corner with a box or similer "cover"... You may be rewarded with escapee sitting atop cage patiently awaiting for the food to emerge. Slap back of head (Yours, not the snakes')