Thanking a Neighbor Who Saved My Baby

My neighbor saved my 12 month old baby’s life, what is an appropriate way to express my

gratitude? We live in an apartment on the 3rd floor. My partner fell asleep while watching

our babies and our 2 year old opened the front door and the 12 month old crawled out.

The neighbor found her on the edge of the stairs. The door is now baby proofed and

my partner feels like a horrible parent. Lots of things could have prevented this

situation and we both failed in that regard. I am just so grateful for my neighbor

and that my baby is unharmed. I don’t know how to express my gratitude. Is it weird to give

them a thank you card with money? Pay their rent for the month? Nothing I can think