You can buy the following 15.6" Acer with a Core i5-5200u, 1080p screen and nVidia 940m graphics chip for $490. It will handle the Sims 4 game just fine without breaking the bank.
However, some people do not like Acer laptops because they felt cheap and are only of average build quality. The following 15.6" Asus has similar specs but it has the current generation Core i5-6200u CPU for $590. People generally tend to like Asus laptops more than Acer laptops. But people gripe about the virtually non-existent Asus tech support...
You can buy the following 15.6" Acer with a Core i5-5200u, 1080p screen and nVidia 940m graphics chip for $490. It will handle the Sims 4 game just fine without breaking the bank.
However, some people do not like Acer laptops because they felt cheap and are only of average build quality. The following 15.6" Asus has similar specs but it has the current generation Core i5-6200u CPU for $590. People generally tend to like Asus laptops more than Acer laptops. But people gripe about the virtually non-existent Asus tech support.
Higher up on the tech tree is the 15.6" Dell Inspiron 7559 for $760 which has a quad core i5-6300HQ, 1080p screen and a GTX 960m which is far more powerful than the nVidia 940m. It's powerful enough to play many big budget games that are graphically demanding like Fallout 4. Overkill for the Sims 4, but at least it will take a while longer before she complains about performance compared to the Acer / Asus laptops.