Account hacked and all chars deleted?

Does my 50/50 hom still remain even tho all my PVE chars were deleted?

Yes, it does.

EDIT: Actually, I've no idea. I'd assumed it did but I actually wouldn't be surprised if once the character with the monument is deleted, it's gone from the HoM forever.

There's no such thing as 'the character with the monument'. The HoM is account based. You can't delete or ged rid of it in any way*. Deleting all your characters will not change the progress in the HoM (you can never downgrade your HoM: points can go up but never down).

*If I recall correctly, getting your account permanently banned means you won't be able to link it to a GW2 account. That's the only way to screw up your HoM.

Test it yourself; create a new character and put that name into the Calculator. As Marty said, it is account based, so you can delete characters and not lose what was reported to the HoM.

I believe the devs have said deleting characters has no effect on the account-wide status, and would have also not change anything already showing on the calculator.