Diabetic With Hypertension Having Fever And Diziness. Diagnosed With UTI And Extremely Low Sodium Level With High Creatanin. Advise?

Question : My mother-in-law ,75, a diabetic for 40 years with hypertension was admitted in hospital,with high fever and severe dizzines. she was diagnosed with UTI and extremely low sodium level with high creatanin. With treatment she improved and was discharged,had good appetite. The next day her abdomen,feet,hands and face was swollen up, difficulty in breathing,stool was leaking out,she felt symptoms of hypogleacemia ,heart palpitations but she walked to the car and then to hospital. They put her in the ICU, told us she was having heart failure ,ejection fraction 25% and almost gave her nothing to eat for 3 days, she became very weak. She was shifted to a room 3 days back after they said all was stable, but is having constant burping, nausea, vomiting any food she is having, motions are smelly and 8/9 times per day,extremely weak ,in diapers ,unable to get up without help,only bones no muscle. She is under nephrology although it is a cardiac problem. How can a person able to walk become so sick after a hospital stay? Is there something wrong with the treatment/diagnosis, is it at all a cardiac failure .There has been no test for ejection fraction after she came into the room. The doctor told she might die suddenly, in six months or a year or two because heart is failing. Please advice , also let us know is this the end , a matter of days or is the nephrologist correct?