(b) That's right. A delivery note is a document that contracting parties should expect to contain contractual terms. In such cases the normal rule is that the terms contained in the document become terms of the contract without further notice. But this only applies to terms that the parties might reasonably expect to find in the document.
The problem in the present case is that the condition, although clearly set out, imposes an unusually heavy penalty for late returns. This is not the sort of term B might expect to find on an invoice or delivery note. In such cases, the party who wants to include the term must make sure it is drawn to the attention of the other party. It seems likely that A has not done enough to make the statement a term of the contract.