Legal Question in Business Law in California

Looking for "72 hour" or "cooling off period" as search terms may get you misdirected in looking for the Civil Code sections. The Code speaks in terms of "three business days" and "right to cancel" or occasionally "rescind" and "rescisson" as verb and noun, respectively. You might start at CC 1682 and work back, and you'll find the most relevant provisions in 1689.5 and here and there in following sections. The code provisions seem to be a mish-mash of general and super-specific laws passed at various times to protect consumers against a variety of general and specific products and services such as "personal emergency response units" dating services, etc. as well as home solicitation contracts in general, meaning any goods or services contracted for outside of something resembling a store or business office. In answer to your specific question, I'd say a three-day wait was in order unless the contract was made at the contractor's place of business, by your mom walking in and negotiating a deal, or perhaps by telephone to their office.