My mom recently passed away, she owned property and sold a piece of property to these people which they would pay there mortgage to her

First let me say that I'm very sorry for your loss.  My mother died a few years ago, and I was the executor of her estate, which was difficult even though I'm a lawyer. I'm not sure what you mean about being the trustee of your mother's trust, since you do not provide any other information about the trust.  However, unless this trust is the mortgage holder, it should not matter. If the mortgage has already been distributed, either to the trust you mention or to some other beneficiary of your mother's estate,  the owner of the mortgage can commence a lawsuit against the mortgagors.  If the trust is the owner of the mortgage, you, as trustee, can commence this lawsuit on behalf of the trust.  However, if your mom was the mortgagee and her assets have not yet been distributed, the representative of her estate would have to commence a lawsuit against the mortgagors.  If you or someone else have been confirmed by the court as the executor or administrator (depending on whether she left a will or not) of your mother's estate, that executor/administrator can start a lawsuit on the estate's behalf.  If not, a representative of the estate will first have to be appointed by the Court.  The laws on how you go about doing this vary from state to state, but it will likely require a separate legal proceeding.  You should consult your local court that deals with wills and estates to find out what you need to do.