Yes, since your husband is already listed as one of the legal owners, he and his grandmother have the right to evict his aunt. Since she has no lease and pays no form of rent (not even utilities, etc.), then she is a guest and can typically be given a 3 day notice to vacate the premises. If she fails to remove herself, then they will need to file for an "ejectment" (this is like an eviction but for a guest instead of a tenant). At this point, he really should consult directly with a local attorney who specializes in land-tenant law, as they can best adivse him how to go about this.