His borther Neil passed away some years back could that have been his widow.
Regarding Neil Reagan, I recall him being asked by a reporter on election night 1980 what he was going to do now that his brother Ronald was President-elect.
"I'm going to get lost," was his reply.
And he did.
That would be my guess too. Her name is Bess Reagan and she lives in Rancho Santa Fe (North San Diego County), CA if I recall correctly.
How close were Ron and Neil?