Decks and Ramps

Submitted to Community Café

I need your help please. I am going to try to clean and seal my moms front and back decks and ramps. As you can see they are in bad shape. I am afraid for my mom who is 74 and walks with a cane and my grandmother who is 93 to even attempt to walk on them when it rains. They are really slick. What I would like to know is the best products to clean and seal them with. These are surrounded by oak trees and don't get a lot of sun. Thanks in advance for any info you can provide.