If they just want them to look more presentable the easiest way is to put some laminatorsplus on them. I have done that several times on rental units in about the same condition and the owners were very pleased with the results.
It's not the same as sanding and refinishing. But, it is helpful for a rental owner that just wants to make the floor more presentable at a much lower price.
E-mail me and I can get you a great deal on a starter kit.