My mom has a difficult time using the bathroom by herself. This poses a very difficult situation for my brother and myself when going out. Any advice?

This poses a difficult situation for my brother and myself mostly when going someplace. So far, I have tried to only go to places where I know we will be only a few hours and I let her use the bathroom before we leave home. But there is the question of what if when we are out she has an emergency and has to use the bathroom. She requires my brother's strength at times to help her up from the toilet and he will not go into the ladies room with her. I hate to use public restrooms in the first place unless absolutely necessary, but if Mom has to use one, I just don't think it would be possible with only my help. We put disposable underwear on her but if she has an accident it can be pretty messy and when home would probably require a shower to clean her properly. Don't want her getting any UTI'S that can be prevented, also. Must try to keep her as clean as possible. Will be a complete nightmare if an accident that is messy, but would have to come home and change her and help her with a shower. All in all, it seems like a no win situation. She just can't go into bathroom alone. And I can't do it alone. Any suggestions? Thanks