My grandmother has emphysema, is her heart more likely to fail?

Yes and No: Emphysema mainly causes dysfunction of the right heart (called cor pulmonale). This usually happens only when the disease is severe/advanced. It can also cause pulmonary hypertension (high pressure in the lungs). Emphysema is usually not a cause of left heart dysfunction although heart disease is very prevalent in patients with copd/emphysema.

Possible: Sometimes, patients with emphysema get elevated pressure in the blood vessels of the lungs due to the destruction of lung tissue. When this happens, the heart can't pump blood as well through the lungs, and it backs up into the legs. This is called right heart failure.

Possibly...: Emphysema is a form of COPD and it can lead to increased pressures in the pulmonary blood vessels. This increased pressure can lead to the heart being less able to pump the blood into the lungs, leading to right heart failure which can then lead to left heart failure. Treatment, including smoking cessation, can hopefully avoid this complication.