She needs to qualify as your dependent in order for you to claim her medical expenses.  Related dependents do not have to live with you.  If the dependent is not related to you, the 2nd home would count if you lived there too, see below:   

• If she is related to you, the dependent does not need to live in the same household as you.  See the list below.
• If she is not related to you, she will have to live with you in the same household the entire year in order for you to claim her as a dependent.  

Certain relatives may qualify as dependents even if they don't live with you:

• Children (including legally adopted), stepchildren, foster children, or any of their descendants
• Siblings, including half and step-siblings
• Parents and their direct ancestors (excluding foster parents)
• Stepparents
• Aunts and uncles, nieces and nephews
• Fathers-in-law, mothers-in-law, sons-in-law, daughters-in-law, brothers-in-law, and sisters-in-law
• Any of these relationships that were established by marriage and not ended by divorce or death.