How long does someone typically grieve for a spouse?

I mean, I know queen victoria did a 40 years, but how long is it for someone not looking to set a record? Like, how long does the whole unwilling to do anything new/resume life part last?

it's been 3 years and I'm starting to worry that I should've really gotten my mom to go to therapy and all, but i didn't want her to think i was just pawning her off on someone cuz i didn't want to deal with her or anything, but I really don't know how I can bring her out of her current state and it's like every time i talk to her, her memory's reset and she's right back to what she used to blaming herself and going over the same stories. She's lost touch with her friends and her relatives all pretty much tried to scam her out of what little we got from what dad left behind, so it feels like I'm the only one she even opens up to at this point. I've tried talking, introducing her to hobbies, cleaning out the house, taking her on trips, encouraging her to go back to work - nothing works. I just want to know how much longer it will take before she pulls herself together.