My 92. yr old dad in starting diuretic now with 44 %ejection fraction and 3rd stage kidney disease. will he maybe get better using diuretics?

No: Diuretics treat one of the symptoms of low ef but do not improve the ef itself because they don't improve the mechanics of the heart. 44% is right on the border between mild and moderate dysfunction. The kidney disease has a bigger role in his overall health, but again, he's 92; all things considered, not too bad for a 10th decade of life.

Diuretic therapy: Yes, he can get a bit better - but diuretic dosage must be adjusted to his response - he could experience excessive response -- so talk to doc about what to monitor - body weight; swelling; blood tests - how frequently.