Find and eliminate musty smell in bedroom and bathroom
It is absolutely unacceptable to have standing water in the crawl space of a pier and beam foundation. I would start with regrading around the house to direct surface water away from the foundation. The goal is to establish a swale about 4 ft from the foundation on any side where the ground slopes up from foundation.

Standing water in the crawl space will lead to a lot worse than a musty odor. It will eventually lead to rot in the beams, floor joists, and sub-floor.

Some people put drains under the soil in the crawl space leading to a sump from which water is pumped out and away from the foundation. Is the soil level in your crawl space below the level of the soil outside? Do you live in an area with a high water table and plenty of rain?