The Ruger equating to the S&W M-686 is the GP-100, not 101. The SP-101 is the one a bit larger than a J-frame.

I'd look for a J-frame and would NOT buy a DA-only model.

THe S&W M-60-4 is excellent, but holds only five shots and is hard to locate. No longer made. The present version with a lock would work, if the lock doesn't interfere.

Depending on hand size, a stainless K-frame would be good. Model 65 with three-inch barrel and round butt would be ideal, or Model 64 for .38 ammo only. I don't think she'll relish firing .357 ammo.

The barrel a fraction over three inches has been an option on the SP-101 for many years, at least since the late 1980's. Early ones took only .38 ammo. I would not buy a .357 smaller or lighter than the SP-101 with three-inch bbl.

Try round butt Pachmayr grips on the Model 64 or 65.

Women vary widely in what they can shoot. I used to know Jo Anne Hall back when she was both a Dallas Cowboys cheerleader and World Champion of the ladies div. in IPSC shooting. She could handle a Colt .45 auto with ease. She was a study in grace and efficiency in using one. Carried a Colt .380 for concealed use. She coached my young son in using the .45 one day in her backyard while my daughter played with her poodle. He told me later that what he learned from her stood him in good stead in combat in Iraq some years later, where he employed 9mm pistols very effectively. The Army gives rather cursory training in pistolcraft to most soldiers not MP's or members of special ops units.

FWIW, one of my favorite fictional characters is Modesty Blaise, in the books. The movies and one TV series were awful. Modesty was a marvelous, very fast shot who could also use a .41 Magnum well at extended ranges. But I'd suggest more gun than her beloved Colt .32 revolver, and she eventually went to a Star PD .45 for routine carry when circumstances didn't require the small size of her MAB .25. But I always suggest a stainless .38 on the J or K frame for real world women who don't know guns well and who will not need more power.

The SP-101 is a fine handgun, but the trigger pull is longer than on J-frames and the action is usually quite heavy. But the heavy mainspring ensures ignition of even tough .357 primers or of some foreign ammo, and my SP is very reliable and quite accurate. In a strong hand, it's a fine gun.
Many women or weak men may need a lighter DA trigger pull. A lot of people have arthritis or neuropathy issues that require a gun that's easy to fire. For them a Walther P-38 or Beretta M-92FS will cycle more easily than will auto pistols based on the Browning locking system. But neither is meant for small hands.

BTW, some French policewomen carried Ruger .38's, maybe even .357's. SP's. Doesn't mean that your lady can, especially if age is a factor, and that's often the case on this board.

I DO NOT suggest Colt revolvers, as they're hard to keep in time and few gunsmiths will now work on them. Too complicated. And the sights are often "off". Otherwise, the Police Positive Special would be ideal with three or four-inch barrel.

And I DO NOT suggest a .22 revolver, as many have VERY sticky extraction. I sold my S&W M-34 in disgust. In a .22, I prefer a Colt Woodsman or a Ruger. The latter is offered in stainless, too. In small .22's, the Beretta M-87 may be the ideal item.