Medical expenses are not dependent care. You have dependent care expenses if your mother lived with you and she was physically or mentally not able to care for herself, so you had to pay someone to care for her so that you could go to work.
Here is how the IRS defines "physically or mentally not able to care for herself," from IRS Publication 503:
"Persons who can't dress, clean, or feed themselves because of physical or mental disabilities are considered not able to care for themselves. Also, persons who must have constant attention to prevent them from injuring themselves or others are considered not able to care for themselves."
