I do not believe the family is involved until evidence of that is made public. Same thing with the delivery driver. I think the person on video at the front door is a man, wearing rimless glasses or plastic safety glasses. The perfectly shaped "eyebrows" are the edge of the glass. The beard and bit of hair under the lower lip looks like a man. The build is masculine, with wider shoulders and narrower hips. In one shot, it looks like he's wearing cowboy boots. In a different shot the shoes appear to be athletic shoes but the video is still too fuzzy. To me, it does look like the delivery driver, but I would not bet on that.
Was it for a ransom? Hard to say. The ransom demand wasn't made until almost 24 hours after it was announced she was missing. The ransom demand could have been made by an opportunist who had nothing to do with NG's disappearance, or it could have been something that the kidnapper thought of after the fact. Either way, it's extortion. If kidnapping was the purpose, the kidnapper usually has it planned, leaving a ransom note when they take the person or very soon after, not 24 hours later, but every case is different.
As for family being involved, I would need to know a lot more about them and their relationship with NG. Everything, like who benefits from her will, life insurance, etc., Who begs for money? Who has she supported in the past, but maybe turned down recently? If someone benefits from her will, I would think they would continue to wait She was 84. Where could they keep her safe and hidden and take care of her? Unless they're amazingly stupid, they couldn't possibly think they could get away with this. People are sometimes amazingly stupid, though, especially when they're desperate.
I think the guy on video is the one. He planned to break in, maybe to rob the place, maybe to attack NG and maybe he planned to kidnap her. He could have been watching the house for a while as in days before. There are rapists who choose elderly victims, so her age doesn't protect her. I think he was probably wandering around in her house while she was asleep and then attacked her. He felt comfortable and safe in her house, so maybe has done something like this before. This time, something went wrong; she may have been killed then or seriously hurt. He could have seen pics of SG and found out this was her mom, or he could have already known that, or he may not have known who she was until her disappearance was on the news. If he had never intended to take her, I think she would have been left in the desert. Why leave the residence and risk being seen carrying a victim?
How did he get in? Has LE said anything about point of entry? Until the video, I thought he could have been waiting inside. Was anything taken, besides NG? If he had taken something, he could have sent a pic of her holding it to prove he was the one who had her. What was in his backpack? A few tools? A cordless drill? Tape? Rope? IDK, but it looked like it contained something puffy, clothes, or maybe a sleeping bag?
Just some ideas.