Will my aunt's will be honored if one of the two persons she has left money for in a trust dies before she does?

If your Aunt is still alive, it would be wise to have her attorney look at the trust and perhaps revise it to be more specific. If your Aunt has already passed, put the trust in the hands of an attorney used to working with trust issues for handicapped persons.  He/she  should be able to set up the trust to care for the remaining beneficiary without interfering with possible government benefits such as medicare/medicaid.  This can be a very technical and critical issue so look for an attorney who specializes in this type case.