Evelyn, this is the only actual reference to Monet Sauce I could find.
Sometimes hotels, restaurants etc. are glad to pass on their recipes.
Your friend could try contacting them.
I have also found this Turkey Marco Polo recipe, but whether the sauce is the one you are wanting, I don't know.
Good luck.
AngelTURKEY MARCO POLO
Servings: 20
Meal Type: Entree
Ethnicity: Mediterranean
Establishments: Restaurant, School
Restaurant: Anthony's
Location: Alabama

Amount Measure Ingredients Preparation
8 Ounces Burgundy
2 Tablespoons chicken base
2 Bay leaves
1 Tablespoon dried thyme
11/2 Tablespoon dried tarragon
1 Teaspoon garlic minced
2 Quarts heavy cream
1/2 Cup cornstarch
5 Pounds broccoli spears cooked and drained
1 5-Pound HICKORY SMOKED BONELESS TURKEY BREAST sliced 1/8 inch thick
11/4 Cups dried bread crumbs
1 Bunch fresh thyme sprigs

Method
Over medium heat, mix together Burgundy, chicken base and herbs. Cook and reduce to a syrup.
Add cream and continue to heat, almost to a boil.
Mix cornstarch with water to make a slurry.
Mix into cream sauce and allow to thicken.
Wrap 2 broccoli spears in one slice of smoked turkey. Nap rolls with Marco Polo sauce and sprinkle with 1 tablespoon dried bread crumbs.
Heat in a 400° F. oven until heated throughout.
Serve 2 turkey rolls with 3 ounces of Marco Polo sauce for each portion.
Serve with garlic mashed potatoes.
Garnish with fresh thyme sprigs.

Recipe provided by Owner Sammy Russo of Anthony's in Birmingham, AL. Arkansas Excelsior Hotel
Three Statehouse Plaza
Little Rock, AR 72201
Phone: 501-375-5000 or 1-800-527-1745; Fax: 501-375-7320

11th ANNUAL PREACHER & WIVES OVER 55 DINNER
Wednesday, June 21, 4:45 p.m.
Arkansas River Valley Room, Excelsior Hotel
$14.50 per person inclusive
See Maxine Dean or Edgar N. (Eddie) Sutton for tickets.

The dinner includes Marco Polo (turkey wrapped in broccoli with MONET SAUCE), dinner salad, starch, hot rolls, dessert, coffee, decaffeinated coffee and tea.