I'm conducting end of life care for my dad in his home. Are there measures for keeping him from attempting to get out of bed unattended?

I did neglect to mention that if you do not have a Hospital bed and all the other equipment that will make it easier and safer for you to care for your dad you should contact Hospice for supplies, equipment and support. You will have the services of a Nurse, CNA as well as a Social Worker, Chaplain and you can request Volunteers to help as well.

If you have hospice they may know what might work. I know when I was in nursing we had these leg bands we could attach that alarmed with positional change, but I am not certain. Do you have a hospital bed from Hospice with rails? Is he getting around the rails?

In home you can use bed rails to try to prevent him from getting out of bed.
You can put the bed as low to the floor as it will go so if he does manage to get out of bed the likelihood of him getting hurt is minimized.
You can use wedges at the side of the bed that make it difficult for him to get over making it more difficult to get out of bed.
You could also try one of the Weighted Blankets that is supposed to help with anxiety. (personally I hated it and returned is, It felt like I was tied down, could not turn or move. but I guess that would accomplish what you are trying to do.
You can also use a Bed Alarm that is placed on the bed. Problem with that is that it may be so sensitive that it will go off with some movements not related to him trying to get out of bed.
There are floor alarms that will alert you if he places his feet on the pad but by then it might be a bit late depending on how fast he is at getting out of bed.
And there are the age old, tried and true Baby Monitors. Some sound only other have a camera.
And lastly there are the cameras you can install and use your phone to monitor.