When should adopt a new cat?

My parents just lost the family cat of 16 years. Although she wasn't keen on others being at the house, she was a big part of the family. This past year, she became especially loving to my mother. My parents are saddened by their loss, have a 4 year old chocolate lab, but knowing how keen they were on cats, I'm not sure exactly how to bring into conversation of adopting a new cat. I know they would enjoy a cat to be around the house, but don't want it to sound disheartening to bring it up. Any helpful hints?