MIL only happy when someone is sitting with her and constantly talking. Any ideas?

We have my long-widowed, 90 yrs Mother in Law on an extended holiday with us to give my husband's brother a break. I love her, and have always got on well with her, and although we live in different country have always had her for month long holidays and gone to stay with her every second month or so for a week at a time.
I am 66 and my husband is 67 and we also care full time for my 89 year old father who lives next door, since Mum went into a local nursing home. Dad is relatively still fit and active, but I do all the shopping with him and cook his meals, and he usually stays for the evening with us watching Netflix etc.
My MIL is now almost blind and wears 2 hearing aids. She is frail and can no longer read, sew, knit etc., or follow her favourite TV programmes.
We sit with her for every meal and tea breaks, and often sit watching TV during the day to keep her company. Every evening we all sit watching TV but she gets bored in between and constantly asks where me or my husband (or daughter who lives nearby) is. If we discuss the TV programme, she says she can't see or hear it, and looks fed up if chat about it.
She wants us to sit down all day chatting to her, and if we go to the bathroom or to ring someone, she comes looking for us if we are away longer than expected.. She comments if we look at our phones or if I go into the next room to my computer (I'm an author! Have taken a year out from writing as I have too many family commitments).
She is always disappointed if we are doing something else, or working in the garden etc. I have given her little safe jobs like washing cups etc., and wiping down worktops, brushing the floor, and simple ironing, but she often comes looking for us to check she is doing it right.
My husband takes her for a walk to the church every day. We also take her out shopping for groceries, but she finds walking around the shops makes her breathless, so sometimes she sits in the car.
We have friends visit or take her with us to their houses, but if we have a conversation she can't join in on due to her hearing or perhaps about colleagues at work, she makes it very obvious that she feels left out. She either sighs loudly or stares ahead, looking crestfallen. All our friends have noticed it. She also comments that our daughter doesn't come often enough or stay long enough, even though she is in full time work and has two little children. She also gets irritated if the focus is on the children, and she doesn't feel included. It's fine if they sit and talk to her.
If me or my husband are out or drop down to my daughter's at night, she will tell whoever is with her that she won't go to bed until she's said goodnight to us. She also wants us to go to bed the same time as her.
Background info: She lived on her own for the last 20 years with no company in the evenings, and was relatively happy with television and phone calls. Last Xmas she took ill, and moved in with my younger brother-in-law and his wife, but they are drained and now thinking she needs full time nursing care.
There are times she will say she is only in the way if I am doing emails etc., which makes me feel guilty.
She eats very little, and I try to think of things she likes plus buying her favourite cakes, sweets etc, but she either doesn't comment on things or gives a muted comment/thanks, which leaves you thinking you never get it right.
Her memory is also starting to go, but I don't think it's dementia causing this, as she has always liked people giving her their full attention, and resented me going out with friends for lunch etc.
Has anyone else experience of this with elderly relatives?
Any ideas that might help or activities that could occupy her?