Just a little comment, there is no such thing as a hypoallergenic dog. It just doesn't exist, it's only a breeder ploy to get people to want a dog, there has been nothing to prove it. Make sure that when you decide to adopt a dog, it visit it first to make sure it doesn't affect your allergies.
Some suggestions for elderly dog breeds that you can go for include the Scottish terrier, the Chihuahua and the Cairn terrier. You can visit a local pet shelter for more suggestions and advice in picking the correct breed. Find more information on the following site http://www.puppy-basics.com/best-dog-breeds-for-the-elderly.html.