You didn't mention what the heart medicine was for and the name of the medicine.
Heart monitors usually go off when their is abnormality.
The age your grandmother died has nothing to do with heart disease
unless she died as a result of heart disease.
Heart disease risk factors for yourself/family history:
-High Blood Pressure
Blue lips can be from many things:
-Low body temperature
(lack of oxygen in blood supply)
-Severe heart problems
I can't tell you if she is safe to ride on an airplane. I don't know anything about her condition. People with certain lung, heart, or vascular problems should not fly. An example would be people who have had blood clots
go to their lungs called a pulmonary embolism
, which they would be on blood thinning medicine for.
Please consult a doctor about flying risk.
Best of luck!