Greetings Sir/Madam.
First of all it's unfortunate on that your mother is bedridden due to various ailment.
Since she's been affected by Nervous system disorder along with
Diabetes, most probably her nerves to various organs would've become weak. Since bedridden, food & water intake will be poor than normal leads her to have problem of difficulty in emptying the bowel leading to
constipation, all results in
bloating. There won't be pain at the initial stage as it is a gradual process & pain comes once something irritate a nearby nerve or she may not feel pain at all.
There are many other reasons to be ruled out apart from bloating due to constipation viz., bladder fullness, intestine obstruction etc.,
Nothing can be done in home other than taking her to nearby hospital in order to find the exact reason & get treated accordingly. I advise you for a Surgeon opinion at the earliest who orders her for scan , scopy ,
enema if required.
Last but not least, take care of your mother very well particularly at this stage.Check to that she's taking medication properly in dose & at right time.Avoid getting complication out
of irregular medication.
Note:
Finally it's just a guidance & not a definitive treatment as i haven't seen your mother personally.I don't know exactly what
your mother condition is unless i see her personally. So visit a doctor.
Hope i guided you right & it helped.