In order for anything to be deductible, your need to be charging fair market rent and reporting it on your tax return. Otherwise, you just have a 2nd home that your are letting a relative live in free or below fair rent and nothing is deductible.
Any capital improvements (but not repairs) to the property are added to your cost basis, for calculating gain or loss, when the property is sold in the future. Gains on the sale of a 2nd home is taxable, but a loss is not deductible (the "personal use" rule, a friend or relative using it is personal use for tax purposes)
