I think your best bet is to just ask. Tell her exactly what you told us here. Hey, before you get here, I just want to work out some details. My dog isn’t great with other dogs so I was thinking about sending him to a doggy daycare or something. Wasn’t sure if you wanted to meet him or how comfortable you would be leaving your guide dog home. What should I do that would make you the most comfortable?
And for any future instances, asking is always the best option. Of course you may inadvertently offend someone but, for the most part, if your intentions are good, I think that comes off clearly. Asking is also always better than taking the decision out of the person’s hands and deciding what would be best on their behalf.
Hope everything works out