Sorry to hear about your Mum, I hope the operation eases the symptoms and gives her some normal quality of life, whether it be for a few months or hopefully more.
I haven't heard of the operation she is having, it sounds quite extensive - more so than the Whipple which is what I and many others with PC tend to have. Although upon reading about it, both operations tend to offer the same results, a way of eating, an opening/removal of bile ducts (gallbladder inc.) and resection of pancreas.
Operation duration - roughly 8hrs
Time in Intensive Care - 2 days
Time in High Dependancy Unit - 2/3 days
Time on normal ward - 14(average) days
She will probably have an epidural for the op and first few days of recovery, she will also have a Patient Controlled Anaelgesic (Morphine) to help keep the painkillers topped up.
There will be several drainage tubes attached, it can look quite scary, but they are necessary and over her stay in hospital they will be removed one by one. However, she will not be able to move for atleast the first week, she will be catheterised and her bowels will not work - so she will not feel the need to get up. She may go home with 3 drainage tubes still attached, to make sure that all is functioning properly before they finally remove them closing access to the work they have done.
She will not be allowed to eat, just suck ice or have her lips dabbed with a sponge - this may last for over a week, until she and they feel it the right time to test the plumbing. It will be liquids first.
She will need to be able to sit relatively upright, as coughing/choking on liquids will cause a lot of pain in the stomach/abdomen - she will need to take great care and chew/swollow slowly.
Food wise (at home):
Importantly, make it small amounts - little and often.
Fresh steamed veg
No meat as it's the hardest to digest
Not too much bread/rice/pasta - keep it small amounts as this can cause bloating
Take Yakult, or better still the acidophilus capsules (much stronger than supermarket drinks) to help with digestion and encourage intestine health
If your Mum is having any part of her pancreas removed, ask for CREON digestive enzymes. It is highly likely that her pancreas will not produce the enzymes for digestion, and this will cause terrible colic/diaorrhea and she will not put any weight on (go straight to the 25,000 and take 1-2 with every meal, 1 for snacks - you cannot overdose, but you can underdose....).
She will not put weight on for a few months anyway as the body's metabolism is in overdrive trying to repair - but she will need max nutrients to help this anyway.
If she cannot tolerate food, ask your GP for nutritional shakes like 'Nutrishake' or 'Ensure' - I found I tolerated the choc flavour pretty well
Hope this helps, if there is anything else you need to ask please do not hesitate - I will try and answer as best I can and so will the other members on here no doubt.
Let us know how your Mum, and you get on, take care.