Giving seller 1 year of occupancy?

[Scott Wang]

I'm purchasing my great aunt's house. She's 76 in failing health. I will move into the house as my own primary residence eventually, but for the next 6-12 months I plan to let her stay in the house. 

I'm drawing up the offer contract now and I'm wondering how to phrase the occupancy in the additional terms section of the offer. She'll have to reimburse me for property taxes and insurance while she lives there, she'll still be responsible for lawn care/etc, and she can stay for up to 1 year. Best way to go about this?

-Scott