How to determine legal ownership of property after bankruptcy and loss of business?

You may need to repost your question with additional information, since it is unclear to whom the trailer was given to, and for what services: was it given by her to the corporation, as an investment (so to speak)? Was it purchased by her, then given by her to some vendor or contractor of the corporation to pay them for services rendered?

As a general matter, who bought someone or how it was paid  for has no particular bearing on the object's ownership or later disposition: what matters is what was done with it. So a trailer given as a gift is the property of the recipient, as would be a trailer given as payment (essentiall barter) for services; a trailer given to the company as a partner's buy-in or investment (so investment in kind, not in cash) would belong to the company; etc. Of course, if the trailer was taken by her without her permission--e.g. she bought a trailer to use; then the company gave it away to a vendor to settle a debt without getting permssion to do so--is a different story. In that event, she can get the trailer back, since no one can give away something to which they do not have title, and the trailer's recipient may be able to sue whomever gave him the trailer under false pretenses.

For a more definitive answer, you need to provide additional detail.