Water Damages to tenant belongings

Hey All! I own a duplex and I live on the 2nd flr Recently there was a toilet leak coming from my unit. I was notified by tenant and I hire someone to come out immediately. Tenant mattress and a few of her pillows were damaged from the water. I know I’m responsible to buy tenant a new mattress. However I need to know How should I go about this situation. Should I give tenant a check for the $600 that she quoted me for the price of her mattress. Or Order tenant a new mattresss? And If I do write her a check should I ask for a receipt?

SN: Plumber told tenant there was mold in the ceiling due to the leak.

I am still fairly new to being a landlord