my advice personally would be to get an adult bird, HOWEVER, this can be tricky because not all hens are compatible, plus you must be careful with quarantining...when I had a similar issue with my own birds, I had a local agricultural fair only a few weeks away that my remaining hen was to be showing at so I was fortunate enough to find a bird there that got along with my surviving hen, and since they were at the fair I didn't have to worry about quarantining.
Many people would prefer to get a chick, because they will have more time with them, the easiest way to do that, is to let her get broody and then one day you just pull one of the eggs out when she gets off and replace it with the chick. POW!!! adoption chicken style (thats how i got mine to raise 10 ducks)