My mother-in-law is suffering from heart failure.

My mother-in-law has been taking medication for irregular heartbeat and other heart issues for about 20 years. She was diagnosed with heart failure four years ago. These days, she manages her condition with medication. Recently, she has been experiencing severe swelling and shortness of breath. As a result, her mobility is becoming increasingly difficult, and her weight seems to be steadily increasing. Her doctor has advised her to control her weight, but it's not easy. In such cases, what kind of assistance would be helpful?