They don't have any rights. A guest--that is, someone who is not a rent-paying tenant but who was allowed to live in a place--has no right to continue living there. The guest may reside there only so long as the person(s) who own or have legal rights to the home allow them to do so, and that permission may be rescinded at any time. The fact that the guest has nowhere else to go is irrelevant: his or her situation does not give her rights to or over another's property, and the property's current owner(s) (e.g. the estate or the heirs) has no obligation to house them. Similarly, that they have children is irrelevant--providing a roof over the children's heads is not the obligation of the property owner(s); and it also does not matter how long he or she has been there, since, as stated, permission to be live there may be rescinded at any time. This person will have to get out: if he or she does not, a legal action may be brought (traditionally called an action "for ejectment") to remove him or her.  This action generally takes several weeks.