Food replacement drinks, and nausea

Hello, I’m looking for some suggestions for my mum please.

The backstory: she became unwell last October, and a large mass was discovered in her womb. This was removed and she was left with damage to her kidneys. Roll forward to May and kidneys have healed enough that catheter is removed and stent put in. 
She had ongoing back / kidney area pain but was told it could be scar tissue, muscles healing etc. 

Then in early September she suddenly loses feeling in her legs, and can’t walk. Blue lighted to hospital to find damaged vertebrae: cancer in spine. Urgent surgery to alleviate pressure, then radiotherapy but nothing works. She is told nothing more can be done. She can’t return home as she needs 24 hour care, as now has no feeling below her ribs. She is placed in a care home.

So we are 3 months along from the diagnosis and she is on a lot of medication for pain. She is on Oromorph amongst other things, but stays in bed a lot as hoisting into her fitted wheelchair is causing too much pain.

She is so nauseated she can’t eat, but obviously needs to. In bed she feels like she is choking if she eats at the angle she has to lie.

I suggested yoghurt drinks or nutritious milk shakes. Are there any other things we could try as she is fading away? We feel she is giving up too, having lost everything in life very suddenly.

Thanks.