After the war was over, mum stored away/put away/ abandoned the pen and paper.
I have stored away[ put aside to wear later] all my clothes
I put away all the clothes [ to put clothes in wardrobe or drawer, to wear later]
"Abandoned" is used to mean to leave and not touch again.If the mother was not going to write ever again after the war, then you can use "abandoned"
If you were never going to put your clothes on again, then you would use "abandoned"