B.C.
If the tomatoes had frost on them they are gone and need to be replanted. I'm not familiar with the eggplant or soy beans.
To prevent the tomatoes from dieing in a frost put four gallon jugs of water around them and place a blanket over the top. The water will supply some heat. The blanket or cloth will tend to keep the cold air off them You could take and ice chest an turn it upside down over your plant. Put the gallon milk jugs full of water inside the ice chest with the tomatoes.
Before I moved to California, I would put a blanket over the tomato plant in the fall to protect it from the first frost. That would usually give me another 2 to 4 weeks of tomatoes. When the first hard frost was coming, I'd pull the tomato plants up by the roots and bring them into a cool Garage and hang them upside down. About 75% of the tomatoes would ripen in the garage.
Good luck and happy gardening.