Final answer:
The healthcare professional should consider fraudulent activity, given only the patient and his son have access to the overdrafted account post Social Security deposit.
Step-by-step explanation:
The healthcare professional should suspect fraudulent activity. Identity theft is characterized by the wrongful acquisition and use of someone's personal information without permission, often resulting in drained bank accounts and large debts. Considering that the elderly patient's Social Security check had been deposited and only two people had access to the account, there's a possibility of fraud, particularly if the son might have misused the account funds. It's also beneficial to consider a bank error or account hacking, but these possibilities might require additional evidence, such as unexpected withdrawals or transactions.