So basically, the daughter handed over a very important document to clover that would immediately financial cripple someone in malicious hands
It's my lack of understanding about what was being said and my lack of understanding of Japanese systems but it looked like a cheque or bank book, and with context clues, it looked like money was involved that's why the mom freaked out so hard in the raw. Basically handing over the family's entire savings
Someone can correct me if I'm wrong
I read 2-3 lastest chps, ML stand up for himself Infront of his fam, and stood by his decision of going to vet school. Dunno much about the father but after mc's word of working in game company the sis actually got a part time job there, and mom realize her own mistake and suggest ML to live other place first because they need space/separation. So ML live with mc in the latest chp, the sis still talk with the clover and mention the clover watch to that person

https://rawkuma.net/manga/kimi-wa-yotsuba-no-clover/
I had to step outside after a scene because I wanted to kill someone