kidney infection drug cocktail ?

Sorry if i appear to sound like im clutching at straws but im trying to help my friend. He's also alone and deaf and is struggling to get any advice

My Best life long friend in the UK has just lost his girlfriend age 23, she died in her sleep leaving 2 children behind. She was on a cocktail of drugs for stomach issues, mainly a kidney infection and mild depression. He was completely against the drugs she was taking but was made out to be stupid, and putting his G/F at risk if she didn't. 2 Years after been put on this list below, she died in her sleep while on a holiday vacation. Almost emmidietly after her death, they remove her heart which they shipped to London, and her body was flown back to Ireland where her family are from. They have found no results as to why she died.

ferrous sulphate tablets, omeprazole gastro-resistant capsules, oramorph oral solution, paracetamol tablets, gabapentin capsules, cyclizine tablets, codeine phosphate tablets, lactulose solution senna tablets, baclofen tablets, buprenorphine patch, amitriptyline hydrochloride tablets.

I'm sure the list of drugs weren't helping her. Her death was UNASCERTAINED
but does he need to look into this as to why the amount of drugs were given.

I live in Asia and i'm going back at the end of the month to help if i can. Just after some opinions on the drugs if possible.

One thing he did say is that she became very violent towards when she was on this medication, and also left the children unattended while he was a work.

Some friends have said that maybe she was hiding things from him, which of course is possible. He does have the death certificate so surely if there was a life threatening problem she was suffering from, surely this would show on the record.

Many Thanks