Any nurses in here? Trying to figure out why 911 wasn't called for my Granny

My Granny died today in her nursing home. They put the cause of death as cancer but they said she was found without a heartbeat at 5am and she was cold. They did CPR but stopped when 911 came because 911 said she was already dead. She's had terminal throat cancer for months so explain to me how she died of throat cancer but was found without a heartbeat. Isn't that a heart attack? She was perfectly fine yesterday. There was no sign she was dying yesterday.

I guess my question is why they didn't start CPR earlier? Like they knew she was dying of cancer so why wasn't she being monitored on a heart monitor and why wasn't 911 on standby?

I tried calling to get answers but the nursing home said they aren't allowed to speak to anyone but my aunt and my aunt is just as confused and mad as I am.

If someone is dying, they need to go to hospital! That's what the hospital is for! Why would you keep her there if you knew she was going to die? She was a full code too but I feel like they just didn't do their jobs.

Edit: we kept her a full code because she had so much more living to do and was healthy. There was no reason to make her a DNR even though they kept telling us she was dying but she wasn't! She was fine! We just saw her yesterday and there was nothing to say she was dying.

Edit: My aunt says that this is why they kept her a full code so she wouldn't die until she was ready. She wasn't ready yet. We refused hospice because she wasn't dying! We weren't ready to give up on her yet. The nursing home kept pushing for things like hospice but we said no, were not interested. They told us we were in denial but we advocated for my Granny. If we hadn't spoken up she probably would have died a long time ago. WE kept her alive because the nursing home just wanted to put her on hospice! They kept bringing in people from hospice and the cancer society and we turned them away. She wasn't dying and they refused to see that! All they say was the fact that she had cancer and wanted to label her a lost cause.