The trustees of the trust can clear the title to this lien. It is important that it be done correctly and that would require a review of the trust and title to your home. If your siblings and the trustee are in agreement that this lien can be extinguished, it should be a fairly easy process but again, must be done correctly.
The caring and knowledgeable attorneys who volunteer for Avvo provide accurate information about the law and legal procedure. It's a wonderful community resource, but it has its limitations. One thing this Q&A is ill-suited to is advising strategy in a specific case. To that end, we can say that the holder of the lien is now the estate of the step-grandmother. How as a practical matter the payment can be made to the estate is impossible to know. Without a will the beneficiaries of the lien payment asset will be the heirs of the estate, which may or may not be you and your siblings.
As you may have perceived by now, the assistance of an experienced probate attorney will be needed.
Best wishes for an outcome you can accept, and please remember to designate a best answer.
This answer is offered as a public service for general information only and may not be relied upon as legal advice.
As an attorney, I have really enjoyed answering questions on AVVO that ordinary, grateful people ask, seeking some guidance -- and FREE guidance at that -- to some thorny legal questions. What I don't enjoy, however, is a sense of entitlement to a quick, in-depth analysis of a weighty legal question as a means of avoiding spending some money on the expert advice of an attorney. I would suggest you contact the Shasta County Bar Association to find an attorney to help you with this question that has seemed to "stump" everyone on AVVO.