homeowners insurance lawsuits

Postman demanding dog in the house?
In December, the woman who has my e sprained his ankle on my front step. She said it happened because was surprised by my dog who jumped to the screen door and cried when she was delivering the mail. We have a very strong steel barred door screen is always closed and so the dog would not leave the house and no way that could have come into physical contact with her. Last week (May, five months after the incident) I got a letter in the mail from a law firm informing me She's suing for that. Is there any way I will be responsible? Can I counterclaim for a claim frivolous? I have homeowners insurance, so I'm sure that any ruling against me would be covered but I am willing to do anything and everything you can to ensure that this woman does not receive a penny on principle alone! I should also mention that the house itself, but I do not live there, my parents. It was his dog, but as I am the owner home, I am that the letter was addressed to.
Total rubbish, get your insurance company and an attorney in question.