My grandaughter is turning two in march and has suddenly started getting up 2 or 3 times a night. How do we get her to go to bed on her own and how do we keep her asleep?

Two is just the right age for acting out in this way. Not staying in her own bed at night. You just have to be firm, grandma, and make her understand that is where she is supposed to be at night. It is going to take a lot of patience but worthwhile in the long run. After all, it is sort of a life lesson that we all had to learn.

Has she been doing any new things lately... even toddlers will wake more when they are learning a new skill.
You can't make her sleep obviously, but you can encourage her to stay in bed. Maybe let her look at books quietly, but she has to stay in her bed to do so.
Is she taking a nap or two during the day? Maybe she will be ready to cut down to just one, or if she is already taking just one, maybe adjusting the time may help.
Be sure there is a bedtime routine to help her wind down at the end of the day.

Well like some of you may know by now I have lots of siblings so might be able to help

First you could probably take her to the park (are do something that includes running or playing) stay for awhile to tire her out. Then try giving her a hot bath every night after doing something that tires her out right before going to bed. Then once you lay her down if she is still awake then read a book or (you while in her roomm while she is in her bed) do something that will make her really bored then soon after most likely she will fall asleep.

And for if she wakes up. What I do is I always make sure there is nothing she can get into in my room so when she wakes up ill just bring her in my room (if she isn't already in there) and close and lock my door so she can't get out with out me knowing then turn off light and lay her down if she gets up that's okay as long as you don't have nothing ahe can get into. Then soon she will end up getting tired and so she might fall asleep on the floor but all you have to do is before you turn off light or lay bak down it would be best to make a pallet on the floor so if she gets tired she could easily get to a bed