It could be as simple as a high-five, pat on the back, praise, a kiss, or a hug. It could also be simple words and actions that could make her mom feel needed around the house since being needed gives the person a feel of being important -- a form of favorable stimulus. To strengthen the independent behavior, Dorothy may choose to remove the aversive stimulus in her mom's environment. If it irritates Dorothy's mom to be looked over most of the day (aversive stimulus in this case) because it reminds her of her disability, she could be allowed to spend the whole afternoon by herself if she was able to go to the bathroom on her own. Her mom can also be allowed to skip a chore she dislikes, such as feeding the dogs (aversive stimulus in this case), if she was able to prepare their breakfast all by herself. Or the aversive...

Dorothy may also talk her mom into doing a task independently. She should be persistent until it becomes a bit annoying for her mom, and so finally complies. When she does, Dorothy should also stop prodding. Dorothy's loud music and her constant prodding are the negative stimulus that can be removed after her mom completes tasks independently.
Behaviors showing independence are likely to occur more frequently with the help of reinforcements. but, in order for Dorothy to reach her goal, it is essential for her to know which stimulus her mother regards as favorable or aversive since her choice of reinforcements -- may it be positive or negative -- largely depends on this.

Works Cited

Santrock, J.W. (2005). Psychology (7th Ed.). McGraw Hill: New York.