Dealing with an elderly relative who is a hoarder can be difficult. Once they are no longer in their house, for whatever reason, that means that you are going to have to clear out their house so that it can be evaluated and then appropriately dealt with. There are things that you are going to have to do to make it easier on yourself.
One thing you need to do is to make sure that you have some protective gear. At the very least, you are going to want to have rubber gloves so that you don't have to touch everything you have to pick up. You may also want to make sure that you have some protective suits. This way you can put them over your clothes and when you are done cleaning so that you can just take off those suits, trash them, and make sure that none of whatever is in the house ends up being taken home with you. These suits should be relatively easy for you to find, and since they are disposable, you shouldn't have to pay a whole lot for enough to get the entire house cleaned. A respirator or dust mask may be a good idea as well, especially if you think that you are going to run into anything that may cause you to have an allergy attack.
Having protective gear is all well and good, but if you won't have anywhere to put all the trash that you pull out of the house, it's going to all be a bit worthless. The easiest way for you to handle it is going to be for you to get a dumpster rental. The company you are working with can bring you a dumpster and put it into position for you. When it's full, you can call them back. They will pick up the dumpster for you and then properly dispose of everything in the dumpster. With the dumpster, all you are going to have to do is toss everything straight into it. You won't have to buy a whole lot of special bags or suchlike. Having the dumpster will make your life much easier and the clean out much easier as well.
If you are going to have to deal with cleaning out an elderly relative's house where they have been hoarding, you are in for a hard job, but there are things that will make your life easier.