my dad was killed in an auto accident,and the other driver pleaded no contest to wrongful death charges,so how long exactly can his insurance co. stal

I'm so sorry for your loss.  Without more specific information, it is difficult for me to determine what investigation the insurance company might be engaging in.  A plea of no contest is not necessarily conclusive if there are other parties involved and there are any issues regarding shared liability.  In general, however, once liability has been settled, the insurance company must determine what the damages are.  If your dad, for example, was employed, the insurer must determine what the loss of his income will be to the family, in addition to other matters.  That can take some time.  Don't be afraid to ask what the status of the claim is and what is taking so long if you believe it is an unreasonable amount of time.  Six months would not be unusual.  If it gets to be much beyond that, however, check with an attorney as well as filing a complaint with the Dept. of Insurance in your state.