The 50s was the era of prepared foods. Think canned vegetables, jello salads, bottled salad dressing, etc. It's also basic American food with hints of other cultures. Chinese food, was egg rolls and chicken chow mien, Italian food was spaghetti, Indian food was unheard of. Vegan was also unheard of, vegetarian highly unusual.
For a very fancy dinner you might have shrimp cocktail followed by roast beef with mashed potatoes and canned green beans with almond slices added, with baked Alaska for dessert. Other appetizers could be celery stuffed with bleu cheese dressing, olives (canned green stuffed with pimento) and cheese (American or cheddar) on crackers, or maybe a basic green salad with green goddess or ranch dressing.
Main courses would be things like steak, roast beef, or beef wellington, served with potatoes and a green vegetable like peas with pearl onions, or green bean casserole. Alternatives would be chicken a la king served over rice or Polynesian chicken served over coconut rice. Polynesian chicken would involve a white sauce, pineapple, maraschino cherries, and maybe coconut.
The best I can come up with that could be vegetarian or maybe vegan is baked spaghetti with tomato sauce, meat balls, and garlic bread. The meat balls can be cooked and served separately.
Desserts could be ice cream, some multi layered jello concoction, chocolate cake, coconut cream pie, etc.
Bruschetta would be unheard of and blinis, if served, would be with caviar for only the most sophisticated people.