Home equals security for Paulina, and also a sense of control. The way in which, as #3 so masterfully points out, she is able to transform her home into a prison and then a court indicates the way that, having survived a period in her life where she had so little control once before, she is determined to be in control now. Of course, the irony of this is that her control is an illusion and is undercut by her husband.
I have to agree with the other posters. From my own interpretation, home means a lot to Paulina. The fact that the man whom tortured and raped her years earlier comes into her home forces Paulina to protect herself and her home. She does not want to feel the same way she did years before, and she decides that she must protect herself now, something she could not do before. All she wishes to do is return the security to her home which she had prior to Miranda's arrival.
Home has an ironically paradoxical importance in the play. Paulina is safe in her home where, paradoxically, she is not even safe with her husband who goes behind her back on decisions that painfully impact her. Her safe home is invaded, again, by danger in the person Miranda, paradoxically dislodging her safety in a location where her safety should be guaranteed by the husband she shares her home with. The safety of her home is turned to the safety of a prison as she turns her home into a prison and then a court. She hopes to purge her soul and home but, paradoxically, will baptize it with more chains of danger as she judges, and most likely executes, Miranda.