Your house. You don't have to leave the heat on over the winter. My daughter is a real estate agent and she tells me that there is a way for houses to be "winterized" so that they can be unheated during the cold months without having the pipes freeze. I think that this involves draining the pipes, among other things. Perhaps you should look into this as a way of saving even more money.
Your Spotty. Have you thought of placing her with a friend just for the season? I have done this for relatives and it always worked out well. The dogs never forget their original family, but they do have a good time here. Also they are safe with someone their human families can trust until it is appropriate for them to go home again.
I live in Missouri, which is not close to you, but if no one else is available I might be able to take Spotty for three or four months, depending.
Surely you have someone you know well who would be able to take your Dal in?
Let us know how it goes, it seems such a shame that Spotty should lose her family because her "grandma" needs help.