At the beginning of Chapter 8, Mrs. Radley dies, and the community hardly notices. Jem and Scout are both upset when they learn that Mrs. Radley died of natural causes. They initially believed that Boo had finally murdered his mother. As was mentioned in the previous post, the children are not concerned about Mrs. Radley's well-being and are more fascinated with her reclusive son's role in her death. At this point in the novel, the children still believe in the rumors and legends surrounding Boo. Mrs. Radley was simply a first-hand witness to Boo's insanity and a possible victim of his malevolent nature. Her death sparks their imaginations as they think of the terrible ways Boo finally killed his mother. As the novel progresses, both children mature and learn that Boo is a kind, shy individual.
The children don't seem to express any feelings whatsoever about her loss, but they do appear to be disappointed that Boo was not the one to kill her, as they had anticipated. This speaks more to them wanting to further the plots of their Boo Radley game than it does to how they felt about Mrs. Radley, whom they had never met.
Sadly, the reaction of the children is probably more of a reaction than anyone else in Maycomb had. Scout says,
Old Mrs. Radley died that winter, but her death caused hardly a ripple" (Ch.8).
Apparently no one really knew her and they only ever saw her when she went out to water her flowers. No mention is made of a service for her, so it is possible the only people outside of the Radley home to really notice her death were Jem, Scout, and Dill.
Jem and Scout were disappointed about Mrs. Radley's death, as shown in this passage:
Jem and I decided that Boo had got her at last, but when Atticus returned from the Radley house he said she died of natural causes, much to our disappointment.
The children were hoping that Boo Radley had harmed her, as they suspected that he would. The children were also hoping to see Boo Radley but, because his brother took over his care, they did not see him after Mrs. Radley passed away.