What kind of charcoal do I use in my house to get rid of musty smells?

You need activated charcoal. Here are bags that you can hang https://amzn.to/2U1e69b

You can put charcoal bricquettes in a bowl and place them in the offending room or you can simply lay a few out in a metal tray. Other options: sew pouches for them or use an old sock, then hang them in inconspicuous areas. Line a basket with foil or plastic and lay the briquettes inside.

Be sure to get natural briquettes without mesquite or easy-light additives.

Activated charcoal buy in bulk online or at fish/aquarium stores

Activated Charcoal. You can find it at Amazon.com & at Walmart

Just click on either one of the BLUE links underlined above and it will take you straight to their website.

Activated charcoal. Amazon sells little netted bags of it to place around your room/s. They also sell sheets of it that you can cut to size and lay in your room vents as well.