The solution to an accessible dishwasher for seniors is to raise the dishwasher 6"-12" so that the top rack of the dishwasher is level with the adjacent countertop.
difficult this is will depend in large part on what type of countertops your mom has. If the countertops are laminate, it would be relatively easy to cut out the top and raise the dishwasher. If the countertops are granite or other solid surface the job will be more involved. To raise the dishwasher, it will have to be removed, have the countertop cut out or removed, and a platform built to support it in the raised location. Then a new top would be installed at the higher location and a panel that matches the cabinetry would be installed underneath the dishwasher. Here's an example:
You might want to consult a consult a contractor to help you make this modification. To find a contractor go to our directory of contractors You might also look at other areas in the kitchen that could be modified to make your mom's life a little easier. Here is an article I wrote on Universal
Design in the Kitchen. Go to this web page
http://roanokeva.com/SNJune/and click on page 12 You can also find more ideas on Universal Design in kitchens at http://www.geappliances.com/design_center/universal_design/