It means that the police believe that the family was targeted because of some relationship, instead of a serial killer or armed robbers looking for whoever left the door open or doesn’t keep large dogs. So the police don’t expect the killer(s) to massacre another family in the neighborhood.

Cash bail is giving the court a lot of money as a pledge that you will show up for your trial. If you show up, you get the money back. The point is that it’s a life-changing amount of money and losing it would be worse than the consequences of being convicted.

Non-cash bail is mostly promising to show up for your court date and not commit any more crimes in the meantime, but there can be restrictions like wearing an ankle monitor and not leaving the state.