Did you, anywhere, mention what state you are in? In any case, the advice is the same, but $80,000 in Mississippi is a little different than $80,000 in California or New York. If she is receiving Food Stamps and Medicaid, premium paid for Medicare, not to mention subsidized housing, those are income based programs, and to get them, she is obviously currently classified as low income. Of course SS retirement isn't income based and isn't affected by a sudden bump in income. People say "SSI" when they are not talking about that specific program.
However, for someone on public assistance programs, in any state, the Medicaid and particularly the housing, an $80,000 gift is a significant bump, with all sorts of ramifications. That your aunt received all of your grandfather's estate, and your mother was still left so low income that she qualifies for all sorts of assistance has made her sudden desire to gift your mother a bit problematic. From your post, you are doing due diligence and sound responsible. What you said about the $80,000 possibly making her life worse instead of better is very true.
I see this situation being almost red flag ripe for accusations of elder financial abuse even if you not were in any way inclined to be interested in doing that sort of thing. I mean, sure, I'll give her what she needs, buy her small things, but arrange for her to keep her benefits, etc. Just send this money to me, auntie. I'll take care of it for her.
That raises enough red flags to get you an investigation by her caseworkers. All it would take is an anonymous complaint call by one jealous or suspicious friend, neighbor, or disgruntled other relative. People love to jump on perceived "welfare fraud."
The whole idea of wiring it directly to you and letting you dole it out to your mother depends entirely on your good character and willingness to do this as your aunt wishes. Once that money has been wired to you and is in your control, you could take a long vacation in the sun with it, and your aunt couldn't do anything much about it. And as for your mother, who probably likes the idea of you having something from your grandfather and would say, "Let the boy have it," if they came after you, she's still opened up to committing welfare fraud. If you do benefit her life in any way financially, it may be noticed. You know this.
When one is on these types of programs, they have completely signed away their privacy and given the program access to all their financial and personal records, and the systems keep very close monitoring of income levels, etc. and would be likely to notice any sudden giftings made to your mother in any significant amounts. They do not ever simply assume that people are telling them the truth about their income and circumstances, they literally go out and check things, and all financial records cross match and are closely audited.
As a person who has been involved with these programs, I strongly, strongly suggest that your aunt, if she wishes to improve her sister's life and share the inheritance with her, speak to an attorney and set up the trust as recommended. She may need your help and counsel to do this.
Depending on your mother's age and health circumstances, even with you totally willing to let her have all of it and doing exactly whatever your aunt wants, if she just takes it directly, gets off the programs she is on, she could have a health crisis and blow through $80,000 in a very short time, and end up with her life much worse than it is now. You pointed this out yourself.
I always cringe when I see these shows and stories on the news channels about somebody who's severely disabled or in really poor health or living in a really bad situation and now they're receiving a sudden gift from some bountiful stranger. This may make good reality tv, we like to think it has solved all their problems. See how wonderfully our system works? And yet in our country today, this is probably going to be just enough to totally mess up their fragile health care and other financial arrangements thoroughly, without offering them any permanent security. Sigh.
Speak with an attorney. Set up a trust that will protect her and keep her current situation working. That's not cheating anyone, including the government and the taxpayers, that's helping your mom, which is what you are actually trying to do.