What are her legal options if she is taxed on profit but received no dividends?

There should be some kind of statement that says whether there is a profit or loss. I would contact the tax accountant to get a copy of the papers he is using to say there is a profit, and then go to the property manager and/or persons who control the investment. The law does not require a distribution just because there is a profit, though there may be something in the documents controlling your mother's investment that gives her distribution rights. This documentation should be reviewed.

More data is needed to answer this question. The tax return of the investment must be examined. Technically, if the investment showed "no profit", in most cases, there would be no taxable distributions to the shareholders.

It is possible that even though there were no "profits" as such, there may have been amounts which are properly taxed as income. The apartment manager should provide you with any documentation that he has presented to the IRS or that he has on file. This may include a copy of the complex's tax return (Is it a corporation, partnership? Has there been a Subchapter S election?). Inquire of the manager whether or not he has filed a Form 1099 with the IRS.

You have more than a tax problem. With respect to taxes, your Mother must be involved in a partnership, limited or general, a corporation or an LLC. For each of those entities, a tax return is filed to determine whether or not tax is owed. The entity would then provide your Mother with an income statement for use on her tax returns. This should be determined in consultation with her tax accountant. It is typical in an estate planning setting to have an entity show a profit but not make a distribution. Although, at a minimum a distribution is made to pay the amount of the tax only. It also sounds like your Mother has an issue with the Property Manager. The Property Manager owes your Mother a fiduciary duty. The Manager must disclose all accounting or other papers involved with the apartment complex on demand. You should have these documents scrutinized by a competent and experienced lawyer to determine if your Mother has a cause of action against the Property Manager. Remember, when it comes to hiring a lawyer, experience counts.