Mobile home seller's obligations?

tell her to call the dealer who sold the home to her

Depends on what the contract said. Chances are she bought it "as is" which means she needs to go to the hardware store and buy it all herself. But tell her to read the contract to see.

Since she's a buyer, it's not like a landlord who has to provide things to a certain standard. This is her problem now, except possibly for the mailbox.

Did she not inspect it and see those items were missing, BEFORE she transferred the money?

If they are not in her sales agreement, them she is on her own. If the mailbox would be attached to the

home,then that is also her responsibility.

What does her sales contract state? There is no law regarding this other than what's in the contract.

As the owner of the home, she is required to provide all of those things herself.

Your daughter owns the home so, guess what? It is HER responsibility to provide those items.