How to handle mom with dementia who keeps trying to find our dad who died last yr? She doesn’t remember his death.

My dad died in November 2019 of alz and other health issues. My mom, his wife of over 60 yrs, has dementia. They had just moved to new ALF. At time Dad was with hospice, Mom was in rehab facility recovering from fall/broken hip. So she wasn’t with him physically when he passed away.

Now, on her many bad days, she wakes up in middle of nite trying to find him. Packs, going home etc. (She has 24/7 caregivers bc of this type of behavior. ) We tried at first to remind her that he’d passed away but she grieved like at the first telling each time. It was hard but my sister, an LPN who lives nearby, was there to console and help. Now after so much heartache along with Covid Non Visitation policy, we decided to say things like “ he’s at hospital” etc. That works for awhile (a few days to a week or so) then the cycle starts again. A couple wks ago, Mom grieved and understood that Dad had died. But she forgets. It’s all heartbreaking.

Anyone have experience with telling truth/grieving, vs stories that seem to work short term?? Or some other idea? We had arranged hospice counselor but Covid stopped that....