I will mention two possibilities, one of which is based on a slightly muffled, fleeting comment Tiffany had made on a much earlier video which may have been before the cancer videos. Unfortunately, I really cannot recall which video, and I don't want to re-watch them. The fleeting comment was something to the effect of the house in which she now lives is the house in which SHE GREW UP (if I understood that correctly.)
1. If that is the case, after her father's unfortunate death, she could have bought the house from her mom. The electric bill remained in her mother's name, perhaps. (I suspect that she inherited funds from her dad, because I really don't see how, with just a few years (maybe five?) of working as an optician she could have afforded such a nice townhouse in a good location.) A significant percentage of that time she worked as a substitute (locum?) optician, driving from center to center as a temporary replacement. That being said, before she moved out on her own after her breakup, she could have lived at home, not paid rent, saved every single cent, and ended up having a sum of money to use as the down payment or to buy the house back from her mom.
The reason I did think that she inherited funds from her dad to buy the house is that
(a) She purchased the house roughly one year after his death.
(b) Even in videos prior to the cancer videos, she didn't seem like the saving sort of person: She pays to have her nails done, pays to have her eyebrows done, spends a lot on clothing, and also gets pedicures because the pedicurist had been surprised not to have seen her for one year (because of her cancer diagnosis.) These services and items are costly, and are not signs of someone who would have saved every cent to buy a house. For me, there is a disconnect between having worked 5 years, maximum, (and who knows if it was full time when she was a substitute optician), routinely spending sums of money for grooming purposes, and having enough money for a down payment on a house.
2. Both the house and the electric bill were in Tiffany's name after she purchased the house, from whomever. Seeing as how Tiffany's health is precarious, maybe she started transferring bills to other names, so that, in case the worst happens, there will be less confusion paper-wise. Tiffany's mum's English language skills look rudimentary, and I don't know how well Tiffany's mum could manage with eventual paperwork, since Tiffany's dad is deceased.
Those are just my thoughts, and I shared them because some things don't add up, literally even.