I am not up to speed with cover and regulations stateside but in the UK it pays to shop around and work out how much cover they need for possessions.
The only things they will need to cover is what they take with you when they move.
Fixtures and fittings and the building itself should be the responsibility of the landlord.
They may want to look into cover outside home as well, as especially if they take gadgets or laptops away from home.
Itemise what they have. Try to speak to someone either face to face, on the phone or live chat online so you can ask the right questions.
After getting about 3 or 4 quotes you'll get the gist of how much you should pay.
Do you have 'excess' in the US? If not don't worry, if you do try to get the lowest possible as the discounts are not worth it. Better to get the most back from a claim.