OP, the first thing that should be done is to review the IDPA rules to determine the type of gun to use.
For example, in the
Stock Service Pistol Div.,
no single action firearms are allowed, which is going to rule out the 1911 platforms. This division is dominated by pistols with barrels at around 5" or so with the majority of them being a Glock 34 (or G17), S&W M&P Pro, Springfield XDM, etc., so something small like a Ruger LC9 or Glock 43 is not even going to be allowed because of the low magazine capacity as noted below.
In the
Enhanced Service Pistol Div., all trigger types are allowed, but again, the dominant guns are larger guns with barrels around 5"
In the
Custom Defensive Div., the 1911 platform rules, but you can only use a .45 caliber handgun, so she is limited to the other two divisions as noted above if she is going to shoot 9MM.
There are two other divisions for revolvers.
Another limiting factor is that the shooter is only allowed to carry 3 magazines, one in the gun, two on the belt. Magazines with more than 10-round capacity can be used, but only a max of 10 rounds is allowed, which is division capacity. Again, going up against larger guns/barrels, your daughter would be at a disadvantage for example if using a LC9 with 6+1 capacity. Simply put, this type of firearm would not be allowed since it does not have enough capacity.
There is also a "power factor" involved, so any shorter barreled pistol may not meet it.
Magazines
During a course of fire, a competitor may have no more than three magazines on them (one in and two on their belt). It is beneficial to bring more with you to a match, since it will expedite preparation for a stage, or allow for quickly topping off you ammo during stages that have multiple strings of fire. But to compete in IDPA, you do not need more than three mags. You are typically better off buying factory magazines, since they are usually superior to aftermarket models. Spend your money wisely and purchase quality magazines, even if you have to make do with fewer magazines in the short term. High-capacity magazines (10+ rounds) are legal for IDPA but you can only load 10 rounds in them.
Edit: Not having shot idpa for several years, I was not aware that a
compact carry division was added this year.