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.
Inaugural Family Photo (standing from left to right) Geoffrey Davis, Dennis Revell, Michael Reagan, Cameron Reagan, President Reagan, Neil Reagan, Dr. Richard David, Ron Junior. (sitting from left to right) Anne Davis, Maureen Reagan, Colleen Reagan, Mrs. Reagan, Bess Reagan, Patricia Davis, Patti Davis, Doria Reagan