If you have had her for 16 days she will birth the pups today, or in the next day or so if she hasn't already. Coco is right about the wheel, it needs to be taken out for the safety of the pups. You can give her;
Boiled/scrambled egg
Tofu
Plain boiled chicken
Porridge (made with water or kitten milk)
wheat germ (good for the pups too - I started to use it around day 5/6, which is when pups start eating solids)
vegetables (preferably ones that aren't gassy)
Cucumber is good for the pups, I also used this sprinkled over the nest, cut into little pieces so the pups can start eating it around 5/6 days of age - they will get additional hydration from this because of the water content.
Seeds and nuts are also good for mum and milk production, pumpkin and sunflower would be good to use.
Baby food (the stuff made for humans, make sure it doesn't contain onions, tomatoes, leeks, seasonings, garlic, spices, and other things hamsters cant have)
There's a huge list here of what hamster can and can't have -
[HAMSTER NUTRITION V] Safe Dietary Supplements for Hamsters - Food & Nutrition - Hamster Hideout Forum
You'll only need enough food for the mum at the moment, try not overfeed because the fresh foods will go bad in the nest which isn't good, and can cause problems to the pups. around 1 week start to increase the amount of food you give. Make sure you're feeding a normal hamster mix as well
I hope everything goes smoothly for her