That's really helpful, thank you Roobarb! I wondered about something like "not impeded" for "Not Impd" - as in, a patient who wanted to discharge themselves, and wasn't prevented from doing so. But "not impaired" seems likely ... although she'd been in this particular institution for 14 years, and another one before that.
I don't know what the nature of Emily's "illness" really was, although sadly, two girls from this family ended up in asylums after their father remarried.