How to structure will? Inheriting house with surviving relative?

[Grant Vincent]

My mom is willing me her house when she passes away. Any suggestions on how to structure the will with specific provisions to allow my stepfather to remain after her death? My heart would like to let him stay for free but I doubt I can afford it and also, I’d like to make sure my interests and his are adequately protected in case this get “squirrelly” in any way. Thought about life estate but really unclear if addressing rent rate or rate index or something is a move people do. Any ideas?

I’d consider keeping it at a rental long-term or may need to sell it. Want to keep options open.