You can narrow the choices down, but make certain there are choices. Simplify the world around them. Too much noise can be distracting as well as annoying. Too much clutter makes locating things more difficult. Pathways around the house need to be cleared of unnecessary papers and objects.
Diversion is a useful tactic when someone is resistance to help.
When a parent is about to repeat a task that has already been done or to repeat a story for the sixth time, gently change the subject to something of interest. Put on his or her favorite music, bring out old photographs, bring up a topic that you know brings back happy memories. If the person becomes irritated, take a break and go back to the task if the emotions have subsided. Sometimes a break is enough to make the person forget that they were annoyed by what was occurring a few minutes earlier. As difficult as it may be, learn to ignore as much as you can.