How To Disinherit Family As A Single Person?

I live in Virginia and Washington DC. I'm single, no kids, no partner. I'm estranged from my mother and brother and I want to make sure they do not inherit my savings and house (in DC) when I die.

I have already removed my mother and brother as beneficiaries from my life insurance, pension/401k, and unpaid compensation. But, I don't know what to do to remove their access to my other money/assets.

Do I need to make a will? How would I begin that process? Sorry, I'm totally clueless as I never expected to be in a position where I'm estranged from my family or have just enough money that I need to worry about this.

Thank you for your help.