The rise in the SNP for a Westminster is due to Labour being perceived as letting down it's heartlands at the Independence vote. The are now called the red tories.In Scotland the rise of the SNP looks likely to displace a lot of Labour MPs north of the border. Ironically this might benefit the Tories. The SNP may well want a Tory government as it is the most likely to sway the hearts of Scottish voters to consider independence next time round.
The SNP do not want a Tory Government. They intend on being in a coalition with Labour. I will be quite happy if the Greens also are in it - that way we may at last have an opportunity to pull the UK back from her ever further move to the right.
There would be a vote on Independence again if the UK voted to come out of the EU but the majority of Scot's voted to stay in which is expected.
The reason the SNP don't want a Tory government is because they will have no say in English politics anymore, and the Scots will see that they will have to raise taxes or cut the freebies that the Scots see as their perks. Scotland can vote for independence and all that goes with it, but don't expect the English to foot the bill when it fails