One pair of Stainless Steel washer hoses with space-saving goose neck end fittings.  They are 6 feet long each.  If you installed a Dryerbox receptacle to be able to move both appliances back against the wall, then in most cases you will need these goose-neck fitting washer hoses.  

Each year in-home flooding causes damages exceeding $170,000,000.  A single washing machine flood costs between $6k and $18k for repairs.