How do I ask for help from friends?

A brief summary: my mom is 90, always been very active and independent, friendly and sociable. She has lots of great friends who call her and invite her often.
Last May my father died, after a long illness; after that she aged instantly, fell ill this summer and lost the sight of one eye. She's now not self-sufficient anymore, she started having lots of memory problems, she's sometimes confused and needs help remembering medicines, appointments etc..

She had a few confusion episodes that really made me worry this past summer so I took her to the neurologist and thanks God she passed the MMSE with full marks; the doctor said she just had a very tough year and that she's emotionally adjusting and recommended lots of socialisation and activities; so I enrolled her in 3 different activities per week and she’s always very happy to go out and very energised when she comes home.

We also have 2 wonderful carers who help us for a total of 5 hours per day, and then I visit her twice a day, one hour in the morning and one in the evening, to make sure she's ok, to chat, play with the cat, have a coffee, help her with medicines, clothes, shower etc...

Still, it doesn't seem enough. Every time she's at home alone for a few hours she gets confused, and depressed. Which I can understand. What I really don't understand is that she never seems able to invite her (many) friends around, commit to their invitations, make plans with them... she's constantly undecided and postpones all decisions til the very last moment, when it’s too late, or simply refuses the invitations for no apparent reason. And to be honest, this has been going on for years; she just waits for people to call her and call her but never call herself, never commits. Even with me!

The result is that I constantly feel terrible because I feel her only emotional support; she never asks me to visit more but she's always sad when I'm leaving. This is starting making me feel resentful, cause it’s true that I’m her only family now, but she truly has lots of people who love her beside me.

I have tried to talk to her friends about the memory problems but it's hard to explain what the problem really is. It seems more like inability to plan and commit. It’s also hard to organise these meetings myself as they call her directly…
I have also started some counselling recently and the therapist suggested to let her carry her own weight. Which I think is a good suggestion, but on a practical level is a bit hard to implement; it’s so hard to see someone going from happy and energised to lonely and confused in a metter of hours, again and again.

Is there a way to ask for help from her friends in this matter, and how? How would you word it? Is this something you would do if you didn't have any family close?

Thank you so much in advance for any ideas!