Reddit reviews Mark Hayes for the Intermediate Pianist: Hymn Settings that Touch the Soul

Sorry you didn't get a reply on here, but generally buying a piano book for someone else as a gift, while a nice thought, probably isn't the best gift unless you know exactly what they want to play. Pianists, especially those who have been playing for awhile, generally know what songs they want to play and have a list of songs they want to play next. Buying a pianist a book that doesn't contain those songs is pretty much just asking for it to go untouched for a long time.

That being said, if you were to ask her what songs she wants to learn next you could google that song and find what book has it and just buy that one.

If you want to keep it a secret from her, I would say buying another Mark Hayes or Dan Forrest book is probably your best bet as she is more likely to play a piece in one of those. Before you just go and buy one of those I would take a look at what books she already owns so you know you aren't getting one that she already owns. If those are at the church and you have no way of looking at them I found a book at the intermediate level by Mark Hayes: https://www.amazon.com/Mark-Hayes-Intermediate-Pianist-Settings/dp/0893282324

And an advanced level by Dan Forrest:

https://www.amazon.com/My-Fathers-World-Advanced-Piano/dp/B006SLEGDW

You would probably want to pick the advanced one because it is more likely for her to have played intermediate pieces than advanced ones.

Finally, you can't go wrong with the best of books as they collect their most popular songs. That being said it is far more likely she has these.

Mark Hayes best of volume 2 (less likely to have this one than the first): https://www.amazon.com/Best-Mark-Hayes-2/dp/1592352391/ref=asc_df_1592352391/?tag=hyprod-20&linkCode=df0&hvadid=266058510895&hvpos=1o3&hvnetw=g&hvrand=2167868115390079040&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9019572&hvtargid=pla-599332514364&psc=1

Couldn't find one for Dan though.

Finally, after everything I said - I can say that while a piano book potentially might not be the best gift because it might never get played. It's the thought that counts and i'm sure she would appreciate your interest in her love for piano more than anything an actual gift can give.