I don't do a Marian hymn, as a rule, but one of our soloists has sung "Ave Maria" as a gift to his mother for years before I was hired. Changing that would cause great ill will, and it isn't worth it.

Always, the ordo and lectionary tell us what is appropriate on any given day. As you have noted, Mothers' Day is not to be found there. Besides, IF one were to perform a Marian hymn on Mothers' Day, one should want to perform a hymn to the Father on Fathers' Day. This would only be right and just. They are, after all, of equal importance.
However, as CharlesW witnesses, there are places where one has inherited an unfortunate 'tradition' that would be very complicated to discontinue. But, if you haven't inherited such a 'tradition', don't create one!

First choice: ignore in the music programming.
Second choice: Regina caeli at recessional.
Third choice: Magnificat (ideally with Eastertide antiphon, mit alleluia) during communion.

Since G3 is now my official "white list" I'm reduced to programming "God of Eve and God of Mary" on Mother's Day. Still, it goes against my better judgement. But since we're officially ignoring the propers anyways, why not go all out?

I do think an Ave for a choral prelude or another Marian hymn for a recessional would be appropriate. But if one were to substitute a Marian hymn for a Marian proper it would best to do this only on a Marian Feast Day, where the Ave is often the text of the Offertory Antiphon (as stated in the above CanticaNova link)

This year Mother's Day fall on Ascension Sunday (in most Diocese where it is transferred) so substituting a Marian hymn for an Ascension hymn (or an Easter hymn in another year) for the Entrance, Offertory or Communion doesn't make liturgical sense, though one could justify a Marian recessional, I think.

It does have most of them, although the Regina Coeli is one glaring omission . I was being somewhat factious. I'm further limited by the only one traditional hymn per Mass rule and I opted for an Ascension hymn. I mean why include a "mother's day hymn" in a "catholic" hymnal anyways. I suppose it could be used a prelude or maybe sung in the narthex coffee-shop.

I will be programming in "On This Day O Beautiful Mother" somewhere in the mix. I considered teaching my choir "O Maria, Madre Mia" (a parishioner of Spanish origin brought that one to my attention once, and I think it would be lovely), but don't have the time this year. Maybe next.

Earl_Grey - Couldn't you do the Sister Act version of Salve Regina?

Adam. Yes. Probably so.

Marian music is never unsuitable for Liturgy. De Maria nunquam satis - with Mary there is never enough!

In fact, as Mary is the bridge between the testaments, the Propers themselves can all be understood as intrinsically Marian: we in the Church pray the Psalms like Mary our Mother (who is the earliest Church) prayed the Psalms. Prophecy points to Mary; the Epistles call us brethren to be Maryform. We experience the events of the Gospel through the eyes of Mary, who accompanied her Son throughout His earthly life. Even the Ordinary and the rubrics of the Mass...but don't get me started.

There's no legal requirement NOT to program hymns to Mary at every Liturgy, whenever incidental music is allowed. I am speaking here of the entire Church year, in every rite and use, and every time and place. One community I know uses the Regina Coeli by Lotti as the Offertory Motet, Concordi Laetitia as the Communion hymn, and "Be Joyful, Mary" as the Recessional - at every Easter Vigil.

Don't let a secular holiday like "Mothers' Day" stop you from programming Marian hymns.

Mother's Day falls in the month of may. A lot of parish churches run by religious orders request Marian Recessionals during May.

My local parish does a special blessing of moms before the end of the mass. There's no need to expound in music Mothers' Day, especially since the homily will also have something about it. In fact the cantors have not programmed a single Marian hymn, which was always done in the past. St. Anne, patron saint of mothers, may not even make it into the canon prayer this Sunday.
At my second parish, the liturgy is devoted to the BVM on a weekly basis owing to the priests being of a Marian order. A whole host of Marian hymns following the final hymn would be sung by the faithful by heart in Latin, although I'm the only accompanist who dares to go there.

thanks jr3672, you said what I was going to say. :)

But, not all Marian hymns are created equal, and the number of other hymns for the temporal and sanctoral cycle mean that you have to be very selective, espeically if you only have two hymns at the procession and the recession. Now, that Mother’s Day is not originally from the church’s calendar, but a Marian hymn in May is fine. The Regina Caeli is probably best, but I am sure there are fine Paschaltide hymns which still can be sung...ymmv.

>> Regina Caeli is probably best, but I am sure there are fine Paschaltide hymns which still can be sung

yes!
apart from Salve Festa Dies, Pascha Nostrum, Pone Luctum, etc,
there is the Gregorian Regina Caeli Laetare, solemn or simple tone, or the polyphonic of this (Lotti, etc) and Regina Caeli Jubila, two of which are in the Secunda Anthologia Vocalis,

and the Gregorian Magnificat with triple alleluias (Cantus Selecti)

We use all of these in Paschaltide.