Swelling can be caused by a variety of factors. Allergies, concussions, edema (water retention) sun burn, insect bites etc. The cure will depend on the cause. In your case since you suspect sun burn to be the cause here are a few home remedies you can try that are effective. Sun burn is caused by the over exposure to the harmful UV ( ultraviolet) rays of the sun. It causes the skin to turn red and become very sensitive. Severe sun burns are generally accompanied with a strong sensation of burning. Sometimes severe inflammation of the sun burnt area is also possible.
The first step to combat any effects of a sun burn would be to drink a lot of water or any other fluid. Apply a mixture of Olive oil and vinegar all over the swollen effected area. This helps in soothing the effected area by reducing the swelling and the sensation of severe sun burn. Aloe Vera is also very cooling and effective. Apply pure aloe Vera gel directly on the sun burnt area. This will bring almost instantaneous relief. Sandalwood is also well known for its cooling properties. Use sandalwood oil to soothe the forehead. Alternatively one can finely powder the sandalwood and make a paste of it by adding water and then applying it all over the effected area. Although it sounds a little extreme finely sliced onion can be put on the forehead of the person suffering from sunburn. Spicy food is absolutely off limits and the person should take cold showers regularly.
As mentioned in your question your wife has swollen eyes too. Here are a few tips to reduce the swelling on her eyelids. Use hot and cold compress regularly while your condition persists. A hot compress is generally effective when one needs to reduce the discomfort because of swelling and the cold compress helps greatly in reducing irritation and itching. Essential oils of lemon & Lavender (a drop each) mixed with a measure of boiled water and applied to the eyelids can cure puffiness and irritation very effectively. In the case of conjunctivitis this is more often than not highly effective. You can One can prepare a very effective lotion using chickweed, milk and tansy. In a cup of milk, you should gently mix in these herbs. Place it on the stove and then bring the mixture to a boil for a few minutes. It should then begin to turn a little viscous. Once the consistency has changed, transfer the mixture from the stove into a container and allow it to cool. You can then apply it on to the swelling for quick relief.