How canI check on a company’s assets regarding a personal injury judgment?

You do not indicate what state you are in: the following process is how you would do this in New Jersey--other states should have similar processes, but they could differ in some details:

In New Jersey, if you have a money judgment against someone, you may serve them with an information subpoena; this is a document requiring them to answer questions regards assets, income, and liability (including bank accounts), and there are penalties, up to imprisonment, which accrue if they do not answer. This is one of the main ways to get information about a judgment debtor.

If you know any banks they used (e.g. from checks or cancelled checks), you could potentially send an information subpoena to the bank to find out what assets at that bank.

If this is an operating bus company, then there is a good chance there have at least some assets--the buses!--you could potentially put liens on or execute against. You could also potentially execute on office equipment or furniture.

If they own any property (e.g. where there office is located), you could put a lien on it.

If the company is a sole proprietorship, not an LLC or corporation, you may be able to recover directly from the owner.

In short, there likely are assets you could use to satisfy your judgment, and ways to obtain more information. There are lawyers who specialize in collecting debts; the best thing to do would be to go to one, and allow him or her to find the money for you. Good luck.