Mil jealous of anytime not spent with her

Bit of background info, mil lost her husband 2.5years ago just a few months after relocating to be nearer us and her granddaughter. Obviously tricky as she has had to navigate settling in a new place alongside grief and bereavement.

We see her at least once a week and she also provides childcare one day a week. She has integrated well to the local community with joining many clubs etc

We've had many ups and downs with her behaviour but the last few weeks have been incredibly hard work, she's constantly trying to pick a fight with us.

Her main grievance is that we don't see her often enough and she regularly threatens to move back to her city of origin. She has fallen out with us this year for having a weekend away as a family of 3, seeing my parents for a celebratory weekend (an important birthday for my father) and for having a birthday meal with my parents(my birthday). This angered her so much she blocked both myself and husband from being able to contact her. Lots of grumbles in between which i'll spare you.

We've just spent this last weekend with her as extended family visited her but as soon as they've left she starts up again that we don't see her enough, she is going to move away etc. She often vocally complains in front of our daughter.

I understand that she's lonely but we can't do everything with her and be made to feel guilty whenever I see my family or we spend time as a family of three. My daughter is now also of the age where she's picking up on what's happening

My husband points out to her she's being unreasonable but is torn between standing up for our family time and supporting her

Any advice/ solidarity/ideas/ viewpoints much appreciated!