So sorry to hear you lost your mum xxx
so I’d say maybe Keep hold of the jewellery for now, and you can decide what to keep at a later date.
bag up and bin things like underwear, well worn shoes etc - things that won’t do anyone else.
keep a few items of clothes if this is something you feel you would like to do. Some people do, others don’t. I’d ask your Dad again if he would like anything to keep. Also if she had make up/perfume etc ask him if he would like to keep any perfume etc and if not I’d say get rid of that kind of stuff.
id say donate anything else or if she had any thing you feel could be sold (I’m thinking coats/jackets/boots/ things that perhaps didn’t get worn as often or were maybe more expensive then maybe try to sell those and donate the money?
there’s no right or wrong thing to do here but I do think your Dad should be a bit more involved, you will be removing her items from their home after all.