Here are some ideas, they can all be found on Amazon.com:
• Install grab bars. Look for the places where your mom normally holds onto when entering or exiting the shower and place the grab bars there.
• Install a tension pole. An alternative to grab bars when getting in and out of a shower or tub is a tension pole from floor to ceiling that would give your mom something to hold on to for balance support.
• Use a bath (transfer) bench. A bath bench eliminates the problem of stepping in and out of the tub/shower. This is how it works: Your mom gets into the shower by sitting down on the bench outside the shower, then the bench slides over the step into the shower, where she can then stand up and shower herself.