Family Trying To Take My Girlfriends House Away.

Location: Indiana.

Hey everyone, I’m posting on behalf of my girlfriend. Shes been really anxious about this situation on top of dealing with grief from losing her grandfather and I wanted to help her get peace of mind. So here’s the situation

Back in 2022, my girlfriend's grandfather gifted her his house for her birthday. They physically went to the county records office together and executed a Warranty Deed. It was stamped and signed by an official state Notary Public and recorded immediately. The property taxes were moved entirely into her name, and she has paid them ever since. Her grandfather had an old will written way before 2022 that originally promised the house to other family members, but this deed completely bypassed probate.
For the first couple of years after the 2022 transfer, her grandfather and her father lived in the house together. Because they were the ones staying there, the utilities were kept in their names. Eventually, local city code enforcement stepped in and declared the house unsuitable because of the hoarding and neglectful living conditions they were causing.
This sparked a lot of family drama. We have texts and voicemails from after the transfer where the grandfather was alert and cussing her out because she had to step in as the owner and remove the father from the property to fix the city violations. It proves he knew exactly who she was and that she controlled the house, though we are a bit worried about what happens if we can't recover those audio files from an old phone.
Over the last year and a half, the grandfather was in and out of nursing facilities, but it was almost entirely for physical rehab. He only started experiencing mental decline, mild psychosis, and hallucinations very recently—within the last year or so. Before that, his mind was totally fine.
He recently passed away, and now the family members from the old will are trying to scramble to get the house so they can immediately sell it for cash. They are actively threatening a lawsuit and hunting for his medical records from 4 years ago, hoping to find an old diagnosis from around the time he signed the deed so they can claim he lacked the mental capacity to sign it over.
We don't have the money for a private lawyer right now, so we are trying to figure out our risks.
Does an old physical diagnosis automatically mean a lack of mental capacity if a state notary verified him at the time? Does his recent mental decline (3 years after the fact) give them any legal leverage to undo a deed signed when he was lucid? Does the utility bill situation hurt her case even though she has the Warranty Deed and paid the property taxes? If they actually serve her papers, what are our options for low-income civil property defense?