emulsifier and stabilizer equivalent to one yolk for frozen desserts I want to make ice cream, sorbet and gelato without eggs. Momofuku's Christina Tosi's Milk Bar cookbook advocates for this and uses gelatin  as emulsifier and stabilizer as well as glucose for thickening instead of the usual full eggs/yolks required by many other books (e.g. one of Ben &amp; Jerry's bases, Ample Hills, Bi-Rite). [UPDATE: the excellent Hello My Name is Ice Cream by Dana Cree avoids using eggs in many of its recipes.]

Modernist Cuisine at Home for their nut butter gelatos also uses tapioca starch and xantham gum as stabilizers (as well as the nut butters themselves, I assume). ChefSteps uses locust bean gum, xantham gum and kappa carrageenan as stabilizers.

What is the equivalent of 


one full egg, and
one egg yolk 


in traditional custard/egg-based ice cream recipes in terms of


gelatin + glucose
tapioca starch + xantham gum
locust bean gum + xantham gum + kappa carrageenan
other emulsifier/stabilizer/thickener combinations?
There is no such thing as "the equivalent" of one yolk, because yolks and other emulsifiers are not the same thing, don't work the same way, and don't have the same results. 

If you are trying to find out how much of a given emulsifier to use, either 1) use a recipe (the preferred way) or 2) find its description (for example in Lersch's book Hydrocolloids, CC lincensed) and see the range. Then work within that range. For xanthan, it is "0.25% thin running sauce, 0.7 - 1.5% thick sauces, 0.5-0.8% foams; [0.07-1%]". "Thin running sauce" is a good description of ice cream base, so you can go with that one as a starting point. You'll have to adjust by experimenting. 

Also, no idea why Modernist cuisine advises both xanthan and starch at the same time, as they are both thickeners. They must have found out through experimenting that some ratio gives an optimal mouthfeel, so take advantage of all the work they have put into it and use that ratio. It is independent of any yolk use in other recipes. If it were just because of a "thickening power" (How would you measure such a thing? Any single-dimensioned measure will be inadequate for kitchen purposes), the mixture wouldn't make any sense.