I’m trying to find the safest bassinet and mattress. Thankyou

Red Nose does not recommend any specific brand of bassinet or mattress.
Red Nose recommends always use a mattress that is firm, clean, well-fitting & flat for a bassinet & cot.
The recommendation for a bassinet mattress is that it is no thicker than 75mm.
https://rednose.org.au/article/bassinets

Are you trying to buy a new mattress for an existing bassinet?
It can often be difficult to find a mattress that fits properly for an older bassinet.