Rent to own trailer with moisture and mushrooms underneath

We had a bunch of rain recently and on of our old rent to owns is very damp underneath, and there are mushrooms growing under it.

The tenant is bothered by the mushrooms and complaining.

Does anyone have any thoughts on this and best ways to treat it?

The dirt should have been sloped so that water won’t stand under the home.
You might try a french drain around the home to guide water away.

Skirting is not sufficiently ventilated. You need to install more screened openings around the skirting to allow the area to dry.
You should have 1 sq. in. of ventilation for every 1sq. ft. of flooring. It needs to be distributed around the skirting. Front rear sides to create cross ventilation.

ny advice on the best way to deal with this dampness and mushroom issue? as i am facing similar issue