Sorry, I haven't read everything. Just wanted to put in my 2 cents.
I've known friends who absolutely need their glasses to drive but will walk around the house at times without them.
To me there are 3 confusing points in the information given:
1 Are they positive she didn't have her contacts in (many times I have more than one pair going. I leave the old pair in my case when I'm ready to trash them and put a new pair in)? If she didn't, the only scenario I see is her answering the door for someone she was expecting.
2 The dogs were in the basement. According to the family they were put in the basement when the family was leaving the house. (Again, she was expecting someone, perhaps planned on leaving with them and put the dogs up)
3 Was it unusual for her to not show up for dinner? The family hasn't said if they tried calling her when she didn't show up. (Could they tell if she ate anything for dinner that night at home? Or could she have made plans to go out with someone?)
I know her wallet was found but what about her id? I've left before with just phone ID and cash/card.