Hello, my name isXXXXX & I'll be helping you today. My goal is to give you a complete & accurate answer that you can understand.
First of all since you aren't currently online, I'll make a couple of assumptions & if they aren't correct, let me know & we can discuss further.
I presume that Tom is the sole member/owner of both LLCs.
I presume therefore that for income tax
purposes Tom's income tax reporting of the LLCs is either on one combined Schedule C or two separate Schedule Cs reporting the activity of each LLC by including the Schedule C(s) on his personal income tax return.
If that is the case, then I must disagree with the previous expert in that no matter how you do the "bookkeeping" it doesn't matter from an income tax standpoint. The reason is that as a sole proprietor there is no tax
reporting of business assets/liabilities except possibly inventory as a component of cost of goods sold & fixed assets as the basis for depreciation computations.
So transactions between the sole member/owner and himself may be handled as "loans or advances" between the LLCs or between either LLC and the Owner or pretty much any other recording method that serves Tom's purpose & doesn't involve any affect on profit or loss.
Therefore, your question as to whether either of your examples in your question are proper, the answer is that both are acceptable. If it were me, and separate sets of books are being maintained for each LLC, I'd use your example (b), because that is actually what was done. There's no problem transferring funds between the LLCs as long as you are the sole owner/member of both LLCs.
If there were other/member owners then that type of a transaction should either be covered in your operating agreement or the transaction should be approved in writing by the managing member and/or all of the owners, as the case may be.