Out of three kids I've had one that just went dry overnight on her own, another who still isn't dry at nights, and the third is dry expect when exhausted (long busy day) or is growing through a growth spurt.
If your not opposed to buying cloth, you might go that route and buy cloth trainers with diaper "doublers" and cover it all with a waterproof cover to catch any leaks. Or you can just do the pullups OVER her panties for night only (explain that once she can stay dry over night she won't have to wear them any more, and that its better then waking up wet and cold)
Or you can buy the waterproof mattress pads or covers (I'd recommend covers only because kids tend to empty full bladders and wiggle around in bed which lead to "spillage" or accidents that aren't caught at all). But if you go that route, be prepared to wake her at night a few hours after she's asleep to make a potty trip. You might find you need to wake her twice durning the night (one a few hours after she's asleep and then again a few hours after that - probably after you've been asleep, if your like most parents and can put the kids in bed before you go to bed).
Of my one who isn't dry at nights still... we've decided that he had the bad luck to inherit the bed-wetting issues that had plagued other family members as kids. He's also a deep sleeper. So you might ask your spouse and family if anyone had troubles with bed-wetting past age 6.
Best of luck!