Hi grang,
Welcome to TP, where you can see, there is wisdom, acceptance, and empathy. Sorry about your distressing situation.
All of these suggestions are excellent, and it's trial and error. It may not work all the time or even some of the time, but it's worth a try.
I don't have any clever ideas but I'd like to ease your anxiety about it all. It reminds me of when I taught Kindergarten. In the early stages, mums would bring their child into class, and sometimes the child would become very upset when mum would leave. Mum would go home feeling wretched, lingering on the image of their baby in such distress, and feeling awful all day. What they didn't realise was that within minutes of mum leaving, the child was settled and happy, all forgotten.
It would be the same in the afternoons, the sheer relief of seeing mum again would bring on a flood of tears. Or if mum was delayed for a few minutes, the child would be happily waiting with me, chatting and calm, mum would appear, and it was tears everywhere! Why did you leave me? Why were you so long?
The moral of my long tale is, mum sees morning tears and afternoon tears and is left wracked with guilt and an emotional wreck thinking of their baby so upset all day. Meanwhile, the child was playing, singing and enjoying the day. Your mum may be so upset when you arrive, spend the whole time wanting to go "home" (as others have said, home can mean comfort and security, not their residence). And then really get upset when you leave. You walk away with that image and think she's distressed the whole time, and feel awful. I'm sure that she settles once you're gone, sadly, she probably doesn't even recall your visit after you've left. Dad has Alzheimer's and lives with Mum in their home still but I'm there every day to support Mum. He would say to her that I hadn't been there for months and when would he see me?
Finally, I don't think of little white lies as deception, I believe it's living in their reality, and it really avoids battles and distress. It's an accepted and kind method of coping, called "Validation Therapy". When you agree with their version of events or reassure them they will go home very soon, you're validating their perception.
I hope your mum settles soon, and you relax a little more about her situation.
Take care, xxx