My bl sugar level drops to 50 3 h after eating,normal insulin, c-peptide, liver enzymes' levels,family history of diabetes,is it reactive hypoglycemia?

Reactive hypoglycemi: yes. It is. Whenever you eat ready sugars or simple sugars( made with table sugar, juices) your body releases lots of insulin . Your sugars get absorbed mostly from stmach and there is still insulin in the blood that continue to lower your sugar.you should avoid ready sugars and take more complex carbs. Along with proteins. You most likely will be developing diabetes in near future. So watch !!