Many more live away from family and friends. Isolation is one of the worst downfalls of getting older in our society. Bringing a pet into the household sounds like a simple way to fix much of this, almost too simple. Make sure they want and can care for the pet. The pet will need daily support in feeding, cleaning, keeping healthy, and even playing.
Pets are very much like children.
Whether the pet is a dog, cat, or even a smaller variety such as a bird, they all need the person they belong too, which in turn makes each of their lives more fulfilling. Where they live will help determine what type of pet they can have. As many elderly people lose a spouse and find they have no need for the large home that they have occupied for years, they find themselves living in much smaller quarters. This means an apartment much of the time, where rules on having pets is determined by the apartment owner. For cases like this, I always suggest a bird or even a small animal like a guinea pig that will not mind spending part of their day in the confines of a cage.