Other posters have pointed out already, but this is an error in how you handle you're money and explained how to do it properly. As a landlord, I do cash checks immediately after getting them because of this exact situation. You shouldn't make the assumption she doesn't need the money either but even if she didn't it is *HERS* and you should have mentally taken it out of your account. I also wondered about the single mother description when her daughters are adults.
This is your mistake, learn from it. Move on and remember not to make it again.