Nice landlord, wet basement issues (renting, house, floors)

[RV0713]

Our landlord is a super sweet older lady whose husband died years ago and has a dependent son with mental health issues. We have been renting from her for several years and she has been great at keeping the property in good shape. The only problem we have is the wet basement. It's a very old house and the only shower is in the basement, plus there's a door to an old coal room which is actually a small dug out area under the side porch. If it rains there is a small stream that runs under the door all the way across to a small drainpipe on the opposite side of the basement. The landlord has said she doesn't have the money to overhaul the entire foundation, and honestly the only stuff we keep down there is stuff that won't get damaged. The worst part is the corner the shower is in. It is behind the drainpipe and the water collects all around the shower and the surrounding floorspace. I basically need the best ways to help control mold/mildew growth on the walls, and tips for what to use as a bath mat/platform thing so we aren't stepping right into the dirty rainwater just after getting clean. Please no negativity-we are close with our landlord and she has been great. I am willing to go down there and scrub it all down once a month if that's what it takes. I just need the best ways to keep this under control until a more permanent solution (or we move) is possible. So far I've just been mopping up excess water or putting down towels to soak it up, and scrubbing the walls.