90 cm is not enough if you rely on aids or help. 120 cm is already tight.
With a bed width of 100 cm or a 200 cm double bed, the normal slatted frame can be removed and the interior of a hospital bed installed. A side effect is that it still looks like a bedroom and not a hospital room.
Since grandma is already unwell, I wouldn't plan with "she can manage now" already.
The bungalow works with a walker and assistance is possible. Wheelchair is not possible and not necessary. Six years ago, I was horrified how quickly large rooms become tight. Between healthy and wheelchair, there are many gradations.Wow, I didn't know that. Our houses with disabled people are all bigger, we never had to measure. One could still move the bathroom a little and gain some width. Bed now 2m wide again:Much more shifting will then be in the kitchen and bathroom.