they are only 4 -5 max 10 ( wallet, keys, cell phone etc), because of that, the proability of becoming a jam would be low I think.
I think you meant "I hope", rather than "I think", and I'm afraid I have to tell you that you will hope in vain.
With a (new) $35 reader from a reliable supplier, if I had TWO tags in a plastic bag, about 4cm from each other....
a) They had to be within no more than 5cm of the reader to be picked up reliably.
b) Presenting both together would result in one or the other... more or less at random... being read. The reader then (good design, even if it isn't what you want) won't read another tag until the one it has "seen" is taken away.
Perhaps what your friend needs is simply a list by the door... "Have you got? Keys? Wallet?..."
(Not as much fun, I know!)
Now... if you want them to PROVE they have those items, that is fairly easy to set up... but will be a pain for the user. Each item will have to be held close to the RFID scanner, separately. THAT could be done.