I know you posted a while ago but only just back on here.
My dad has same, dual illness. When he first started getting up in night we put a safety gate a the top of the stairs, kept lights on on landing and bathroom and the OT got grab rails installed. Important thing though was taking lock of bathroom door so he couldnt lock himself in! All that helped him and keep him safe. This worked but as mobility decreased we got sides on bed. This did stop him getting up. Didnt cause any distress either. Surprised to see you can get sides for a double bed too which meant he could stay with my mum longer. Few years on now and he is downstairs in a electric bed, sides on etc. All put in place by OT.
Hope you are both getting as much support as possible and best of luck.